Plated polymer fan

ABSTRACT

Plated polymeric gas turbine engine parts and methods for fabricating lightweight plated polymeric gas turbine engine parts are disclosed. The parts include a polymeric substrate plated with one or more metal layers. The polymeric material of the polymeric substrate may be structurally reinforced with materials that may include carbon, metal, or glass. The polymeric substrate may also include a plurality of layers to form a composite layup structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application Ser. No. 61/844,048 filed on Jul. 9,2013, entitled “Lightweight Gas Turbine Engine Components Produced ByPlating Molded Polymer Article,” and to U.S. Provisional PatentApplication Ser. No. 61/844,025 filed on Jul. 9, 2013, entitled “PlatedPolymer Fan Blade and Method of Making.”

TECHNICAL FIELD

This disclosure relates to methods for plating metallic layers ontomolded polymeric articles for producing lightweight plated polymercomponents for gas turbine engines. More specifically, this disclosurerelates to a method that includes molding a polymer article having adesired geometry and then plating the outer surface of the polymerarticle with metallic layers using electroless plating, electrolyticplating, or electroforming methods to produce lightweight metal partsthat can be incorporated into gas turbine engines.

BACKGROUND

Metal parts tend to be heavy due to the high densities of most metals.In certain instances, removing material from a metal part can lead toweight savings. For example, the stresses imposed upon a metal part inservice may be analyzed. Typically, there are areas of the metal partthat have little or no stress as well as highly stressed areas. An idealmetal part may contain a sufficient amount of metal in highly stressedareas to transmit the necessary loads and perform the function of thepart. However, such an ideal part would contain less or no material inareas with little or no stress, respectively, thereby reducing theweight of the metal part to an idealized minimum Therefore, there is aneed for improved methods of providing metal parts that are lightweightbut strong enough in high stress areas to perform the function of thepart.

However, removing material from the metal part by conventional means,such as machining, laser drilling, etc., is both difficult and costly.Further, removing material from a metal part can lead to reducedmaterial properties of the part, which may be unacceptable. Thus, simplyremoving metal from a formed metal part is less than ideal in certainparts and situations.

Gas turbine engines designed for aircraft include thousands of metalparts. Because the weight of an aircraft, including the engine, isdirectly related to fuel consumption, engine and aircraft manufacturersare constantly seeking new technologies that will help them reduce theweight of their engines and aircraft respectively. One strategy involvessubstituting traditional metal parts for lightweight polymer orcomposite parts. For example, non-metal containment structures for gasturbine engines may include, for example, KEVLAR® (a registeredtrademark of E.I. Dupont de Nemours & Company) or another ballisticfabric wrapped around a case. Containment systems that include fabricare more weight efficient than all-metal containment cases, butnonetheless add weight to the engine.

Additive manufacturing (AM) or three-dimensional (3D) printing is aprocess of making a three-dimensional solid object of virtually anyshape from a digital model. AM is achieved by depositing successivelayers of material in different cross-sectional shapes. AM is considereddistinct from traditional machining techniques, which mostly rely on theremoval of material by methods such as cutting or drilling, i.e.,subtractive processes. A materials printer usually performs AM processesusing digital technology. Since the start of the twenty-first centurythere has been a large growth in the sales of these machines, and whilethe price has dropped substantially, AM remains costly. Despite its highcost, though, AM is used in many fields, including aerospace.

Less costly alternatives to AM include various molding processes, suchas blow molding, injection molding, compression molding, and others thatwill be apparent to those skilled in the art. Blow molding processesbegin with melting the molding material and forming it into a parison orpreform. The parison is a tube-like piece of plastic with a hole in oneend through which compressed air can pass through. The parison isclamped into a mold and air is pumped into the parison. The air pressurepushes the molding material outwards to match the interior surface ofthe mold. Once the molding material has cooled and hardened, the moldopens and the part is ejected. In contrast, injection molding includesinjecting molding material for the part into a heated barrel, mixing,and forcing the molding material into a mold cavity where the moldingmaterial cools and hardens to the configuration of the cavity.Compression molding is a method of molding in which the preheatedmolding material is placed in an open mold cavity. The mold is closedand pressure is applied to force the material into contact with all moldareas, while heat and pressure are maintained until the molding materialhas cured.

For many molding processes, hard tooling is used to form the mold ordie. While hard tooling can provide a high dimensional repeatability,hard tooling is very heavy and cumbersome and can present a safetyhazard when moved or handled. Further, fabricating hard tooling is timeconsuming and costly. As a result, hard tooling is normally tooexpensive and time consuming for short production runs and/or for thefabrication of test parts. Thus, the ability to quickly fabricatetooling to support short production runs and/or test runs of compositematerials is desired.

Blow molding and injection molding cannot be used if the polymer to bemolded is in the form of a composite with a plurality of layers orplies, i.e., a composite layup structure. Composites are materials madefrom two or more constituent materials with significantly differentphysical or chemical properties that, when combined, produce a materialwith characteristics different from the individual components. Theindividual components remain separate and distinct within the finishedstructure. Typically, composite layup structures can be molded or shapedusing compression molding, resin transfer molding (RTM) or vacuumassisted resin transfer molding (VARTM), all of which utilize hardtooling that typically include details machined into one or more blocksof metal that form the mold.

Composites can also include reinforcing fibers or matrices. The fibersor matrices may be formed from ceramic, metal, combinations of ceramicand metal, concrete and various other inorganic and organic materials.Organic matrix composites (OMCs) may include polyimides and/orbismaleimides (BMIs) because they can be used at higher temperaturesthan other commonly used organic reinforcing materials, such as epoxies.Such high-temperature OMCs may be processed by autoclave molding,compression molding, or resin-transfer molding. These processes allrequire lengthy cure and post-cure cycles as well as hard tooling thatis difficult and costly to make. Further, only tooling with limitedgeometrical complexity can be produced. Thus, improved methods formolding OMCs are also desired.

One inexpensive method of forming a metallic layer on a surface of amolded polymer article is electroless plating. To ensure adhesion of theplated film to the molded polymer article, the surface of the polymerarticle may need to be prepared by etching, abrading, or ionicactivation. The most common types of metals used for plating on polymersare copper, silver, and nickel, although other metals can be used.

Electrolytic plating is the deposition of a metal on a conductivematerial using an electric current. A molded polymer article must firstbe made conductive to be electrolytically plated. This can be donethrough electroless plating or by the use of conductive additives suchas carbon. The article to be electrolytically plated is immersed in asolution of metal salts connected to a cathodic current source, and ananodic conductor is immersed in the bath to complete the electricalcircuit. Electric current flows from the cathode to the anode, and theelectron flow reduces the dissolved metal ions to pure metal on thecathodic surface. The anode is usually made from the same metal, and candissolve during the electroplating process, thereby replenishing thebath.

The operating temperature of a plated polymer article, component or partmay be limited by the polymeric substrate. Thus, parts for a gas turbineengine may not be able to be fabricated from a polymer material or areinforced polymer material if the part is within a line-of-sight to aheat source, such as a combustor, which may transfer heat to the part byradiation. Because of the operating conditions of a gas turbine engineand the need to save weight, lightweight polymer parts that canwithstand relatively high operating temperatures for polymers (>150° C.)are needed in the aircraft and/or gas turbine engine industries.

Another issue associated with gas turbine engines is noise. Suppressionof gas turbine engine noise has become an important field of researchdue to airport regulations and aircraft noise certification requirementsthat govern the maximum noise level that aircraft are allowed toproduce. Further, because the principal sources of noise from acommercial aircraft are the engines, reducing noise emitted by suchengines is desirable. Thus, there is a need for gas turbine enginestructural components that are both lightweight and that include soundattenuation properties.

SUMMARY

Plated polymer components for gas turbine engines are disclosed. Thedisclosed components may include a molded polymeric substrate platedwith at least one metallic layer and, optionally, at least one polymerlayer.

Methods are also disclosed for fabricating such plated polymercomponents of gas turbine engines. The disclosed methods may includeforming a polymer into a desired shape having an outer surface. Themethod may further include preparing the outer surface to receive acatalyst and activating the outer surface with the catalyst. The methodmay then include plating a first metal onto the outer surface and thecatalyst to form a structure, and optionally followed by plating one ormore additional layers until a desired thickness is reached. The platedstructure may optionally be coated with a polymeric coating.

In accordance with an aspect of the disclosure, a fan component for agas turbine engine is provided. The fan component may include at leastone polymeric substrate forming the fan component and having at leastone exposed surface. The fan component may also include at least onemetallic layer deposited on the at least one exposed surface of the atleast one polymeric substrate.

In accordance with another aspect of the disclosure, the at least onepolymeric substrate may be formed into at least one of a root, aplatform, and an airfoil of a fan blade.

In accordance with yet another aspect of the disclosure, the at leastone polymeric substrate may be formed into one of a fan case, an iceimpact panel of the fan case, an airfoil, a discrete fan platform, and ashroud for the airfoil.

In accordance with still yet another aspect of the disclosure, theairfoil may be a fan inlet guide vane.

In further accordance with another aspect of the disclosure, thediscrete fan platform may include at least one endwall.

In further accordance with yet another aspect of the disclosure, the atleast one endwall may be polished.

In further accordance with an even further aspect of the disclosure, theat least one metallic plating layer may be selectively deposited on theat least one exposed surface providing vibration control.

In further accordance with still an even further aspect of thedisclosure, the at least one metallic plating layer may be selectivelydeposited on the at least one exposed surface providing an electricalgrounding path.

In accordance with another aspect of the disclosure, a gas turbineengine is provided. The gas turbine engine may include a plurality ofairfoils. Each airfoil of the plurality of airfoils may include a firstat least one polymeric substrate having a first at least one exposedsurface. A first at least one metallic plating layer may be deposited onthe first at least one exposed surface.

In accordance with yet another aspect of the disclosure, the engine mayinclude a fan case surrounding the plurality of airfoils. The fan casemay include a second at least one polymeric substrate having a second atleast one exposed surface. The fan case may also include a second atleast one metallic plating layer deposited on the second at least oneexposed surface.

In accordance with still yet another aspect of the disclosure, at leastone ice panel may be disposed on the fan case. The at least one icepanel may include a third at least one polymeric substrate having athird at least one exposed surface and a third at least one metallicplating layer deposited on the third at least one exposed surface.

In further accordance with another aspect of the disclosure, the enginemay include a plurality of discrete fan platforms with a single discretefan platform of the plurality of discrete fan platforms disposed betweenadjacent airfoils. Each discrete fan platform may include a second atleast one polymeric substrate having a second at least one exposedsurface and a second at least one metallic plating layer deposited onthe second at least one exposed surface.

In further accordance with yet another aspect of the disclosure, theplurality of airfoils may be fan inlet guide vanes.

In further accordance with still yet another aspect of the disclosure,the plurality of airfoils may extend from at least one shroud. The atleast one shroud may include a second at least one polymeric substratehaving a second at least one exposed surface and a second at least onemetallic plating layer deposited on the second at least one exposedsurface.

In further accordance with an even further aspect of the disclosure,each discrete fan platform of the plurality of discrete fan platformsmay include at least one endwall. The at least one endwall may include athird at least one polymeric substrate having a third at least oneexposed surface and a third at least one metallic plating layerdeposited on the third at least one exposed surface. The third at leastone metallic plating layer may be polished.

In accordance with another aspect of the disclosure, a method offabricating a fan component for a gas turbine engine is provided. Themethod entails forming at least one polymeric substrate in a desiredshape of the fan component. Another step may be depositing at least onemetallic plating layer on at least one exposed surface of the at leastone polymeric substrate.

In accordance with yet another aspect of the disclosure, the desiredshape may be one of a fan case, an ice impact panel of the fan case, anairfoil, a discrete fan platform, and a shroud for the airfoil.

In accordance with still yet another aspect of the disclosure, thedesired shape may be at least one of a root, a platform, and an airfoilof a fan blade.

In further accordance with still yet another aspect of the disclosure,the at least one metallic plating layer may be selectively deposited onthe at least one exposed surface.

In further accordance with an even further aspect of the disclosure, theat least one metallic plating layer may be polished.

Other aspects and features of the disclosed systems and methods will beappreciated from reading the attached detailed description inconjunction with the included drawing figures. Moreover, selectedaspects and features of one example embodiment may be combined withvarious selected aspects and features of other example embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a gas turbine engine.

FIG. 2 is a partial sectional view of a gas turbine engine illustratingan engine static structure case arrangement on the lower half thereofwith an accessory system mounted thereto.

FIG. 3 is a perspective view of a disc-shaped hub equipped with aplurality of dovetail-shaped slots that extend through an outerperiphery of the hub and a single fan blade with a dovetail-shaped rootthat has been received in one of the dovetail-shaped slots of the hub.

FIG. 4 is a cross-sectional view of a portion of a prior art fan bladeroot, showing wear and damage typical to conventional designs.

FIG. 5 is an enlarged partial cross-section of a fan blade root.

FIG. 6 is another sectional view of a gas turbine engine.

FIG. 7 is a partial sectional view of a disclosed structure thatincludes a polymeric substrate plated with one or more metallic layers.

FIG. 8 is a partial sectional view of a disclosed sound attenuationstructure that includes a honeycomb structure sandwiched betweenpolymeric substrate layers.

FIG. 9 is a partial sectional view of another disclosed structure thatincludes a polymeric substrate plated with one or more metallic layersand a heating element embedded in the polymeric substrate.

FIG. 10 is a partial sectional view of yet another disclosed structurethat includes a polymeric substrate plated with one or more metalliclayers and a heating element sandwiched between the polymeric substrateand the plated metallic layer(s).

FIG. 11 is a sectional view of a gas turbine engine, particularlyillustrating an exhaust tail cone disposed within a core nacelle that isdisposed within a fan nacelle.

FIG. 12 is a partial sectional view of a sound attenuation panel thatmay be used for at least part of an inner barrel or an outer barrel of anacelle, such as a core nacelle or a fan nacelle.

FIG. 13A is a partial sectional view of an inlet to fan nacelle that maybe fabricated from a plated polymeric substrate in accordance with thisdisclosure.

FIG. 13B is an enlarged partial sectional view of the fan nacelle inletshown in FIG. 13A.

FIG. 14 is a partial perspective view of a compressor airfoil clusterthat may be fabricated from a plated polymeric substrate in accordancewith this disclosure.

FIG. 15 is a partial plan view of a variable geometry radial guide vaneassembly.

FIG. 16 is a partial perspective view of a disclosed piston rod formedfrom a polymer tube that is coated with one or more metallic layers (notshown in FIG. 16).

FIG. 17 is a partial perspective view of another disclosed piston rodformed from a polymer tube that is filled with a high density foambefore being coated with one or more metallic layers (not shown in FIG.17).

FIG. 18 is a partial perspective view of another disclosed piston rodformed from a polymer tube with metal end plugs, that is filled with ahigh density foam and that is coated with one or more metallic layers(not shown in FIG. 18).

FIG. 19 is a partial perspective view of yet another disclosed pistonrod formed from a polymer tube with metal end plugs, that is filled witha high density foam and that is coated with one or more metallic layers(not shown in FIG. 19).

FIG. 20 is a sectional view of a disclosed instrument probe that may befabricated from a plated polymeric substrate in accordance with thisdisclosure.

FIG. 21 is a sectional view of a plated polymeric substrate.

FIG. 22 is a partial side view of a low-pressure compressor stage thatmay be fabricated from a plated polymeric substrate in accordance withthis disclosure.

FIG. 23 is a side view of a polymeric substrate selectively plated witha metallic layer that provides a grounding strip.

FIG. 24 is a perspective view of a disclosed airfoil that may befabricated from a plated polymeric substrate in accordance with thisdisclosure.

FIG. 25 is a sectional view of the airfoil of FIG. 24.

FIG. 26 is a sectional view of a disclosed duct that may be fabricatedfrom a plated polymeric substrate in accordance with this disclosure.

FIG. 27 is a perspective view of a fan platform that may be fabricatedfrom a plated polymeric substrate in accordance with this disclosure.

FIG. 28 is a perspective view of gas flow directing members, each in theform of an airfoil supported by a platform having a three-dimensionalpolymeric substrate plated with one or more polished metallic layers inaccordance with this disclosure.

FIG. 29 is a sectional view of a disclosed sound/vibration damper ordampening structure made from a plated polymeric substrate in accordancewith this disclosure.

FIG. 30 is a sectional view of another disclosed sound/vibration damperor dampening structure made from a plated polymeric substrate.

FIG. 31 is a sectional view of a drive or torque transmission shaft madefrom a plated polymeric substrate in accordance with this disclosure.

FIG. 32 is a sectional view of a plated polymer fan case ice panel madein accordance with this disclosure.

FIG. 33A is a disclosed sectional view of a plated polymertube/connector for use in a lubrication system of a gas turbine engine.

FIG. 33B is an enlarged partial view of an end of the tube/connectorshown in FIG. 33A.

FIG. 34 is a perspective view of a plated polymer gearbox cover made inaccordance with this disclosure.

FIG. 35 is a perspective view of a prior art nose cap and spinner.

FIG. 36 is a perspective view of a disclosed plated polymer forwardcone.

FIG. 37 is a perspective view of another disclosed plated polymerforward cone.

FIG. 38 is a sectional view of yet another disclosed plated polymerforward cone and a disclosed plated polymer attachment ring.

FIG. 39 is a sectional view of a textured plated polymeric substratemade in accordance with this disclosure.

FIG. 40 is a sectional view illustrating the dimensional parameters fora structural rib molded into a polymeric substrate that is plated withat least one metallic layer and optionally covered by at least onepolymer layer.

FIG. 41 illustrates four rib patterns that may be molded into thepolymeric substrate shown in FIG. 40 for enhancing impact resistantproperties of the substrate.

FIG. 42 illustrates in irregular grid pattern for rib(s) that may bemolded into the polymeric substrate of FIG. 40 for enhancing impactresistant properties of the substrate.

FIG. 43 illustrates two additional patterns of protrusions and recesses,respectively, that may be molded into the polymeric substrate of FIG. 40for enhancing impact-resistant properties of the substrate.

FIG. 44 is a cross section view of a turbofan engine.

FIG. 45 is a perspective view of a fan blade having a metal layercovering a non-metallic core.

FIG. 46 is a cross sectional view of the fan blade of FIG. 45 takenalong the line 3-3 showing the non-metallic core and metal layer.

FIG. 47 is a side view of another embodiment of a metal plated fan bladehaving a non-metallic core.

FIG. 48 is a side view of another embodiment of a metal plated fan bladehaving a non-metallic core.

DESCRIPTION

FIGS. 1 and 6 are partial schematic views of a gas turbine engine 110suspended from an engine pylon P within an engine nacelle assembly N,which is typical of an aircraft designed for subsonic flight. The enginepylon P or other support structure is typically mounted to an aircraftwing W, however, the engine pylon P may alternatively extend from otheraircraft structure such as an aircraft empennage or tail assembly.

The gas turbine engine 110 may include a core engine C within a corenacelle 112 that houses a low-pressure spool 114 and a high-pressurespool 124. The low-pressure spool 114 may include a low-pressurecompressor 116 and low pressure turbine 118. The low-pressure spool 114may be coupled to drive a fan 120 either directly or through a geartrain 122. The high-pressure spool 124 may include a high-pressurecompressor 126 and a high-pressure turbine 128. A combustor 130 may bearranged between the high-pressure compressor 126 and the high-pressureturbine 128. The low and high-pressure spools 114 and 124 may rotateabout an engine axis A.

The engine 110 may be a high-bypass geared architecture aircraft engine.Airflow enters a fan nacelle 134, which at least partially surrounds thecore nacelle 112. The fan 120 communicates airflow into the core nacelle112 to power the low-pressure compressor 116 and the high-pressurecompressor 126. Core airflow compressed by the low-pressure compressor116 and the high-pressure compressor 126 is mixed with the fuel in thecombustor 130 and expanded over the high-pressure turbine 128 andlow-pressure turbine 118. The turbines 128 and 118 are coupled to thespools 124 and 114 to rotationally drive the compressors 126 and 116,respectively, and the fan section 120 through the optional gear train122. A core engine exhaust exits the core nacelle 112 through a corenozzle 138 disposed between the core nacelle 112 and the tail cone 132.

Containment Cases and Other Structural Components Made from PlatedPolymeric Substrates

Referring to FIG. 2, engine static structure 142 includes sub-structuressuch as a core engine case structure 144 often referred to as the“engine backbone.” The engine case structure 144 may include a fan case146, an intermediate case (IMC) 148, a high-pressure compressor case150, a diffuser case 152, a low-pressure turbine case 154, and a turbineexhaust case 156. The core engine case structure 144 may be secured tothe fan case 146 at the IMC 148, which includes a multiple ofcircumferentially spaced radially extending fan exit guide vanes (FEGVs)136.

Because it does not experience high operating temperatures, the fan case146 may be fabricated from one or more shaped polymer articles, each inthe form of a reinforced polymeric substrate that has been coated withone or more metallic layers. Suitable thermoplastic materials mayinclude, but are not limited to: polyetherimide (PEI), polyimide,polyether ether ketone (PEEK), polyether ketone ketone (PEKK),polysulfone, polyamide, polyphenylene sulfide, polyester, polyimide, andcombinations thereof. Suitable thermoset materials may include, but arenot limited to, condensation polyimides, addition polyimides, epoxycured with aliphatic and/or aromatic amines and/or anhydrides, cyanateesters, phenolics, polyesters, polybenzoxazine, polyurethanes,polyacrylates, polymethacrylates, silicones (thermoset), andcombinations thereof. Optionally, the polymeric material of thepolymeric substrate 52 may be structurally reinforced with materialsthat may include carbon, metal, or glass. The fiber-reinforced polymericsubstrate may be molded or may include a plurality of layers to form acomposite layup structure.

An exemplary case 146 may include a metallic layer 196 plated onto thepolymeric substrate 195 as shown in FIG. 7. The substrate 195 may be afiber-reinforced resin (continuous or discontinuous). Either woven ornon-woven fibers may be used, such as continuous unidirectionalfiber/tape, woven fabric, discontinuous long fiber, or chopped material.

A polymeric substrate 195 may be molded into a desired shape. One ormore metallic layers 196 may be deposited onto the polymeric substrate195 to form a part for a gas turbine engine, such as a fan case 146. Aswill be apparent to those skilled in the art, other parts may befabricated using this technique as well. The metallic layer(s) 196 maybe applied by electroless plating, electroplating, or electroformingwith a thickness ranging from about 0.01 inches (0.254 mm) to about 0.5inches (12.7 mm) This thickness range may provide sufficient resistanceto wear and impact and/or provide sufficient material for post machiningto meet tight tolerance requirements.

The plated metallic layer(s) 196 may include one or more layers. Theplating may consist of one or more metals selected from nickel, cobalt,copper, iron, gold, silver, palladium, rhodium, chromium, zinc, tin,cadmium, and alloys with any of the foregoing elements comprising atleast 50 wt. % of the alloy, and combinations thereof. Plating may beperformed in multiple steps by masking certain areas of the moldedarticle to yield different thicknesses or no plating in certain areas. Acustomized plating thickness profile can also be achieved by tailoredracking (including shields, thieves, conformal anodes, etc.). Tailoredracking allows for an optimization of properties for the case 146 withrespect to heat resistance, structural support, surface characteristics,etc. without adding undue weight to the case to accommodate each ofthese properties individually. Thus, plating thicknesses may be tailoredto the structural requirements of the case 146. In addition, a thickerplated metallic layer allows for more aggressive machining, finishing,etc. to achieve the desired surface roughness, tolerances, etc. incertain locations of the case 146. Use of a multi-step process allowsfor optimization of cover properties, with respect to fire, structuralsupport, surface characteristics, etc. without adding undue weight tothe case 146.

Some mounting features (e.g., flanges, bosses, mounting holes, integralfittings) may be bonded to the molded polymer article using a suitableadhesive after molding but before plating. Further, the polymericsubstrate can be fabricated in multiple segments that are joined by anyconventional process (e.g., by welding, adhesive, mitered joint with orwithout adhesive, etc.) before plating. Furthermore, molded compositearticles may be produced and plated separately and subsequently bondedby transient liquid phase (TLP) bonding. In addition, features such asbosses or inserts may be added (using an adhesive, riveting, etc.) tothe plated structure after the plating has been carried out. Thepolymeric substrate may have a thickness ranging from about 0.05 inches(1.27 mm) to about 2 inches (50.8 mm).

Layshaft Covers

Referring to FIG. 6, an accessory gearbox 160 is mounted to the casestructure 144 generally parallel to the engine axis A. The accessorygearbox 160 takes advantage of the significant axial area within thecore nacelle C (FIG. 1) to support an engine accessory system 162 whichmay include accessory components (ACs) such as an air turbine starter(ATS), a deoiler (D), a hydraulic pump (HP), an oil pump (OP), anintegrated drive generator (IDG), a permanent magnet alternator (PMA), afuel pump module (FPM). It should be understood, that any number andtype of accessory components AC might alternatively or additionally beprovided.

The gearbox 160 houses a gear system that couples a towershaft 166 to alayshaft 168. The layshaft 168 is disposed within a layshaft cover 176,which is a cylindrical or tubular structure as shown in FIG. 6. Thecover 176 may be fabricated from a shaped polymer substrate 195 that isplated with one or more metal layers 196 as shown in FIG. 7. Forstrength, it may be advantageous to form the shaped polymer substratewith a composite layup structure. The polymeric material may selectedfrom the group consisting of: polyetherimide (PEI), polyimide, polyetherether ketone (PEEK), polyether ketone ketone (PEKK), polysulfone,polyamide, polyphenylene sulfide, polyester, polyimide, and combinationsthereof. Suitable thermoset materials may include, but are not limitedto, condensation polyimides, addition polyimides, epoxy cured withaliphatic and/or aromatic amines and/or anhydrides, cyanate esters,phenolics, polyesters, polybenzoxazine, polyurethanes, polyacrylates,polymethacrylates, silicones (thermoset), and combinations thereof.Optionally, the polymeric substrate 195 may be structurally reinforcedwith materials that may include carbon, metal, or glass. Thefiber-reinforced polymeric substrate 195 may be molded or may include aplurality of layers to form a composite layup structure.

A composite layup structure may be compression molded into a desiredshape to form a shaped composite article that will serve as a substrate.One or more metallic layers may be deposited onto the composite shapedarticle to form a part, such as a layshaft cover 176. As will beapparent to those skilled in the art, other parts may be fabricatedusing this technique as well. The metallic layer(s) may be applied byelectroless plating, electroplating, or electroforming with a thicknessranging from about 0.004 inches (0.102 mm) to about 0.05 inches (1.27mm) This thickness range may provide sufficient resistance to wear andimpact and/or provide sufficient material for post machining to meettight tolerance requirements. As noted above, the plated metalliclayer(s) may include one or more layers.

Plating may be performed in multiple steps by masking certain areas ofthe molded article to yield different thicknesses or no plating incertain areas. A customized plating thickness profile can also beachieved by tailored racking (including shields, thieves, conformalanodes, etc.). Tailored racking allows for an optimization of propertiesfor the part or layshaft cover 176 with respect to heat resistance,structural support, surface characteristics, etc. without adding undueweight to the layshaft cover 176 to accommodate each of these propertiesindividually. Thus, plating thicknesses may be tailored to thestructural requirements of the layshaft cover 176.

For example, a thicker plated metallic layer can be provided on the oneside of the cover 176 for structural integrity during a fire. Inaddition, a thicker plated metallic layer allows for more aggressivemachining, finishing, etc. to achieve the desired surface roughness,tolerances, etc. in certain locations of the cover 176. Use of amulti-step process allows for optimization of cover properties, withrespect to fire, structural support, surface characteristics, etc.without adding undue weight to the cover 176.

Some mounting features (e.g., flanges, bosses, mounting holes, integralfittings) may be bonded to the molded composite article using a suitableadhesive after molding but before plating. Further, the shaped polymeror composite article can be fabricated in multiple segments that arejoined by any conventional process (e.g., by welding, adhesive, miteredjoint with or without adhesive, etc.) before plating. Furthermore,molded composite articles may be produced and plated separately andsubsequently bonded by transient liquid phase (TLP) bonding. Inaddition, features such as bosses or inserts may be added (using anadhesive, riveting, etc.) to the plated structure after the plating hasbeen carried out. When the shaped polymer article is formed from acomposite material and is to be used as a substrate to be plated for useas a part like a layshaft cover 176, the molded composite article mayhave a thickness ranging from about 0.05 inches (0.127 mm) to about 2inches (50.8 mm).

For some parts with complex geometries and/or that are large,multi-piece mold toolings are required because the molded part cannot bereliably released from a single mold. Thus, to fabricate tooling forsuch a part with complex geometry and/or that is large, the part may bedivided into a plurality of segments, which may be coupled. Possibleweak points caused by the joining of two segments together may beovercome by joining the two segments using one or more joints incombination with an adhesive that remains within the joint so that theadhesive is not exposed or “visible” to a subsequent plating process.The types of joints that may be suitable for coupling two such polymersegments together include mitered joints, angled joints, angled-miteredjoints, welded joints, mitered joints with low-angle boundaries, miteredjoints with accommodation channels for accommodating extra adhesive,welded joints with a cover, slot-type attachments with or without anadditional fastener, and others as will be apparent to those skilled inthe art. Types of welded joints may include, but are not limited toultrasonic, laser, friction, friction-stir, and traditional weldedjoints. Adhesive may also be used to couple the substrates or shapedpolymer articles together. Then, the joined segments are plated usingone of the plating methods described above. By plating one or morelayers over the joint and over the outer surfaces of two segments,possible structural weak points created by the coupling of the twosegments can be avoided. Suitable adhesives include epoxy-basedadhesives in liquid, paste, or film form, with long-term servicetemperatures of up to 121° C. (250° F.), and bismaleimide-basedadhesives with service temperatures up to 177° C. (350° F., in paste orfilm form). In addition, cyanoacrylates and polyurethanes could be usedin certain situations, depending upon the strength and rigidityrequirements.

The plating material and thickness may be selected such that astructural analysis would indicate that the plated metallic layer 196will take the majority of the loads that the part experiences.Furthermore, geometric features are optionally added into the design tomitigate any weakness caused by joining segments together prior toplating.

Portions of the metallic layer(s) 196 may be purposefully weakened (orthe polymeric substrate can be masked before plating) to provide pathsfor outgassing and expansion of the polymeric substrate during a fire.As will be apparent to those skilled in the art, such weakened portionsshould not reside near areas of the part that are significantly stressedand such weakened portions may be masked areas, scored lines, one ormore large holes, smaller holes, etc. to provide appropriate redirectionof thermally induced stresses and strains away from critical load paths.

Selective Plating of Fanblades to Customize Properties

Turning to FIG. 3 a fan blade assembly 211 may include a plurality offan blades 230 mounted to a disc-shaped hub 231. More specifically, thedisc-shaped hub 231 may include an outer periphery through which aplurality of dovetail-shaped slots 233 extend. The dovetail-shaped slots233 may each include inner surfaces 234. The inner surfaces 234 may eachbe disposed between inwardly slanted walls 236 and 237 that extendinwardly towards each other as they extend radially outwardly from theirrespective inner surfaces 234. As also shown in FIG. 3, thedovetail-shaped slots 233 may each accommodate a dovetail-shaped root238 of a fan blade 230. The dovetail-shaped root 238 may be connected toa blade 239 that includes a leading edge 241 and a trailing edge 242.The leading and trailing edges 241 and 242, respectively, may bedisposed on either side of the blade tip 243.

As shown in FIG. 4, the dovetail-shaped root 238 may include an innerface 244 that may be disposed between and connected to inwardly slantedpressure faces 245 and 246. The pressure faces 245, 246 may each engagethe inwardly slanted walls 236 and 237, respectively, of theirrespective dovetail-shaped slot 233.

As shown in FIGS. 4-5 and explained above, the pressure faces 245 and246 may undergo significant wear due to their engagement with theslanted walls 236 and 237, respectively, of the hub 231. To alleviatethis situation, the dovetail-shaped root 238 may be selectively platedto produce resistance to wear, environmental factors, etc. The disclosedmethod may be applied to fan blades 230 made from a variety of materials(e.g., metals, polymers, composites, and ceramics). One or more metalliclayers 251 and 252 may be applied to the root 238 by electrolessplating, electroplating, or electroforming to local thicknesses rangingfrom about 0.0005 to about 0.015 inches (from about 12.7 microns toabout 381 microns). More specifically, the metallic layers 251 and 252may be applied to any one or more of the pressure faces 245 and 246, theinner face 244, radially inward portions of the airfoil 239, andcombinations thereof as shown in FIG. 5.

Thus, improved fan blades are disclosed that may be fabricated from avariety of materials including metals, polymers, polymeric composites,and ceramics. The strength of the roots of such fan blades may beenhanced by selectively plating at least part of the fan blade root,especially at the pressure faces, as discussed above. Plated moldedthermoplastic or composite airfoils, airfoil clusters, and inlet guidevane assemblies offer cost and weight savings compared to traditionalmetal components.

Airfoil Clusters

Turning to FIG. 1, an aircraft gas turbine engine 110 may be dividedinto two sections: the cold section and the hot section. The coldsection includes the inlet air duct 255, the compressor(s) 116, 126 andthe diffuser (not shown), which is disposed upstream of and connected tothe combustor 130. The hot section includes the combustor 130, theturbine(s) 128, 118 and the exhaust passageway 256.

The compressor(s) 116, 126 each include airfoils or airfoil clusters asshown in FIG. 14. Referring to FIG. 14, a vane cluster 260 for acompressor 116, 126 includes a radially outer shroud 261, a radiallyinner shroud 262 and two or more airfoils 263 extending radially betweenthe shrouds 261, 262. Hooks 264 at the axial extremities of the outershroud 261 facilitate its attachment to an engine case, not shown. Feet265 at the axial extremities of the inner shroud 262 accommodate aninner air seal, also not shown. The cluster 260 extendscircumferentially between lateral extremities 266. When several suchclusters 260 are installed in a gas turbine engine 110 (FIG. 1), theshrouds 261, 262 define the radially inner and outer boundaries of aportion of an annular fluid flow path 267. The flow path 267circumscribes the engine axis A (FIG. 1). A typical vane cluster 260 maybe a hand layed-up, compression molded, and two-dimensional laminate ofa graphite-epoxy material system. However, this manufacturing processtends to be rather complex (e.g., ply orientations have to be tightlyand repeatably controlled, and are applied manually).

A disclosed airfoil cluster 260 may be formed from a polymeric substrate195 and at least one plated metallic layer 196 as shown in FIG. 7. Theexemplary substrate 195 may be an injection-molded or compression moldedarticle formed from at least one material selected from the groupconsisting of: Suitable thermoplastic materials may include, but are notlimited to: polyetherimide (PEI), polyimide, polyether ether ketone(PEEK), polyether ketone ketone (PEKK), polysulfone, polyamide,polyphenylene sulfide, polyester, polyimide, and combinations thereof.Suitable thermoset materials may include, but are not limited to,condensation polyimides, addition polyimides, epoxy cured with aliphaticand/or aromatic amines and/or anhydrides, cyanate esters, phenolics,polyesters, polybenzoxazine, polyurethanes, polyacrylates,polymethacrylates, silicones (thermoset), and combinations thereof.Optionally, the polymeric material of the polymeric substrate 195 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 195 may be molded ormay include a plurality of layers to form a composite layup structure.

The plated metallic layer 196 may include one or more layers. The platedmetallic layer 196 may be applied by electroless plating,electroplating, or electroforming to a thickness ranging from about0.001 to about 0.05 inches (from about 25.4 to about 1270 microns),locally. The average plating thickness may range from about 0.004 toabout 0.025 inches (from about 101.6 to about 635 microns). Thicknesseswithin these ranges provide resistance to erosion, impact, FOD, etc. andthe option to finish more aggressively to meet tight tolerances, surfacefinish requirements, etc. The plated metallic layer 196 may include anynumber of metals or alloys including, but not limited to, The platingmay consist of one or more metals selected from nickel, cobalt, copper,iron, gold, silver, palladium, rhodium, chromium, zinc, tin, cadmium,and alloys with any of the foregoing elements comprising at least 50 wt.% of the alloy, and combinations thereof

Plating may be performed in two steps by masking certain areas of theairfoil cluster to yield different thicknesses in areas of interest,such as the cluster platforms. This customized plating thickness profilecan also be achieved by tailored racking (includes shields, thieves,etc.). In addition, a thicker plated metallic layer allows for moreaggressive machining, finishing, etc. to achieve the desired surfaceroughness, tolerances, etc. This multi-step process allows foroptimization of airfoil cluster properties, with respect to fire,structural support, surface characteristics, etc. without adding undueweight to the part to completely accommodate each of these properties.

More broadly, the airfoil cluster 260 can be fabricated in multiplesegments that are joined by any conventional process (e.g., ultrasonic,laser, friction, friction-stir welding; traditional welding processes;adhesive; mitered joint with or without adhesive) before plating.Furthermore, the airfoils 263 and shrouds 261, 262 may be produced andplated separately and subsequently bonded by transient liquid phase(TLP) bonding.

Plated polymer parts offer cost and/or weight savings compared totraditional materials and processes. For example, plating providesbuilt-in erosion protection and superior resistance to loads. Further,additional savings can be realized given the high-throughput ofcurrently available molding and plating processes. Finally, complexgeometries can be accommodated by producing the airfoil clusters 260 inmultiple polymer segments and joining them together before plating.

Thus, airfoil clusters are disclosed that may be fabricated from avariety of materials including metals, polymers, polymer composites andceramics. The strength of the shrouds of such airfoil clusters may beenhanced by selectively plating at least part of the airfoil clustershrouds. Plated molded thermoplastic or composite airfoils, airfoilclusters and inlet guide vane assemblies offer cost and weight savingscompared to traditional metal components.

Plated Polymer Airfoils

Hybrid airfoils for gas turbine engines are used to replace metalairfoils to reduce weight and manufacturing costs. For example,US20120082553 discloses an airfoil with a polymer core and an outernanocrystalline metal shell that covers the polymer core and whichdefines an outer surface of the airfoil. The nanocrystalline metal shellhas a thickness ranging from about 0.001 to about 0.125 inches (fromabout 25.4 to about 3175 microns). U.S. Pat. No. 4,815,940 disclosesanother hybrid airfoil having a graphite fiber-reinforced polyetherimidecore covered by a very thin copper conductive layer that is covered by anickel, cobalt or nickel-cobalt plated layer having a thickness rangingfrom about 0.002 to about 0.02 inches (from about 50.8 to about 508microns). As the need to replace heavy metal parts with lightercomposite and composite plated parts for gas turbine engines continuesto exist, additional hybrid airfoil designs are needed.

Plated injection molded thermoplastic airfoils are disclosed that reducemanufacturing and operating costs of a gas turbine engine and thatprovide integral erosion and foreign object damage (FOD) resistance.Further, the plating can be locally varied in thickness to allow theairfoil structural properties to be tailored to the specific need.Further, the disclosed airfoils provide improved bond strength relativeto the prior art because the plating contributes to the structuralintegrity of the airfoil versus being simply an erosion protectionlayer.

Turning to FIGS. 24-25, an exemplary airfoil 340 may include a polymericsubstrate 341 and an outer metallic layer 342. The substrate 341 may beinjection-molded or compression molded and formed from at least one ofthe following: polyetherimide (PEI), polyimide, polyether ether ketone(PEEK), polyether ketone ketone (PEKK), polysulfone, polyamide,polyphenylene sulfide, polyester, polyimide, and combinations thereof.Suitable thermoset materials may include, but are not limited to,condensation polyimides, addition polyimides, epoxy cured with aliphaticand/or aromatic amines and/or anhydrides, cyanate esters, phenolics,polyesters, polybenzoxazine, polyurethanes, polyacrylates,polymethacrylates, silicones (thermoset), and combinations thereof.Optionally, the polymeric material of the polymeric substrate may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate may be molded or mayinclude a plurality of layers to form a composite layup structure.

The metallic layer 342 may include one or more layers. The metalliclayer(s) 342 may be applied by electroless plating, electroplating, orelectroforming to a thickness ranging from about 0.001 to about 0.025inches (from about 25.4 to about 635 microns), locally. An averageplating thickness may range from about 0.003 to about 0.02 inches (fromabout 76.2 to about 508 microns). These thickness ranges provideresistance to erosion, impact, FOD, etc. and the option to finish moreaggressively to meet tight tolerances, surface finish requirements, etc.

Thus, airfoils are disclosed that may be fabricated from a variety ofmaterials including metals, polymers, polymer composites and ceramics.The strength of the roots of such airfoils may be enhanced byselectively plating at least part of the airfoil root, especially at thepressure faces, as discussed above. Plated molded thermoplastic orcomposite airfoils, airfoil clusters and inlet guide vane assembliesoffer cost and weight savings compared to traditional metal components.

Inlet Guide Vanes

The inlet air duct 255 of the gas turbine engine 110 of FIG. 1 mayinclude an inlet guide vane assembly 270 as shown in FIG. 15. The inletguide vane assembly 270 may include an outer shroud 271, an inner shroud272 and two or more vanes 273 extending radially between the shrouds271, 272.

Similar to the airfoil cluster 260 discussed above, the disclosed inletguide vane assembly 270 may be a hand layed-up, compression molded,two-dimensional laminate of a graphite-epoxy material system. As notedabove, this manufacturing process tends to be rather complex (e.g., plyorientations have to be tightly and repeatably controlled, and areapplied manually). Therefore, a disclosed inlet guide vane assembly 270may be formed from a polymeric substrate 195 and at least one platedmetallic layer 196 as shown in FIG. 7. The exemplary substrate 195 maybe an injection-molded or compression molded article formed from atleast one material selected from the group consisting of: may include,but are not limited to: polyetherimide (PEI), polyimide, polyether etherketone (PEEK), polyether ketone ketone (PEKK), polysulfone, polyamide,polyphenylene sulfide, polyester, polyimide, and combinations thereof.Suitable thermoset materials may include, but are not limited to,condensation polyimides, addition polyimides, epoxy cured with aliphaticand/or aromatic amines and/or anhydrides, cyanate esters, phenolics,polyesters, polybenzoxazine, polyurethanes, polyacrylates,polymethacrylates, silicones (thermoset), and combinations thereof.Optionally, the polymeric material of the polymeric substrate 195 may bestructurally reinforced with materials that may include carbon, metal,or glass.

Further, the substrate 195 may be a two-dimensional woven laminatedcomposite that includes carbon fibers or glass fibers in combinationwith an epoxy resin or a similar matrix material. Metal inserts may beincorporated into the substrate 195 to enhance the load-carryingcapability of the resultant structure.

The plated metallic layer 196 may include one or more layers. The platedmetallic layer 196 may be applied by electroless plating,electroplating, or electroforming to a thickness ranging from about0.001 to about 0.003 inches (from about 25.4 to about 762 microns),locally. The average plating thickness may range from about 0.003 toabout 0.025 inches (from about 76.2 to about 635 microns). Thicknesseswithin these ranges provide resistance to erosion, impact, FOD, etc. andthe option to finish more aggressively to meet tight tolerances, surfacefinish requirements, etc. The plated metallic layer 196 may include anynumber of metals or alloys including, but not limited to, nickel,cobalt, copper, iron, gold, silver, palladium, rhodium, chromium, zinc,tin, cadmium, and alloys with any of the foregoing elements comprisingat least 50 wt. % of the alloy, and combinations thereof

Plating may be performed in two steps by masking certain areas of theairfoil cluster to yield different thicknesses in areas of interest,such as the cluster platforms. This customized plating thickness profilecan also be achieved by tailored racking (includes shields, thieves,etc.). In addition, a thicker plated metallic layer allows for moreaggressive machining, finishing, etc. to achieve the desired surfaceroughness, tolerances, etc. This multi-step process allows foroptimization of airfoil cluster properties, with respect to fire,structural support, surface characteristics, etc. without adding undueweight to the part to completely accommodate each of these properties.

More broadly, the inlet guide vane assembly 270 may be fabricated inmultiple segments that are joined by any conventional process (e.g.,ultrasonic, laser, friction, friction-stir welding; traditional weldingprocesses; adhesive; mitered joint with or without adhesive) beforeplating. Furthermore, the vanes 273 and shrouds 271, 272 may be producedand plated separately and subsequently bonded by transient liquid phase(TLP) bonding.

Plated polymer parts offer cost and/or weight savings compared totraditional materials and processes. For example, plating providesbuilt-in erosion protection and superior resistance to loads. Further,additional savings can be realized given the high-throughput ofcurrently available molding and plating processes. Finally, complexgeometries can be accommodated by producing the inlet guide vaneassembly 270 in multiple polymer segments and joining them togetherbefore plating.

Thus, improved inlet guide vanes are also disclosed that may befabricated from a variety of materials including metals, polymers,polymer composites and ceramics. The strength of the shrouds of suchinlet guide vanes may be enhanced by selectively plating at least partof the shrouds. Plated molded thermoplastic or composite airfoils,airfoil clusters and inlet guide vane assemblies offer cost and weightsavings compared to traditional metal components.

Radiation Heat-Resistant Metal Plated Polymer Components for Gas TurbineEngines

Because of its lightweight and high specific strength, metal platedpolymers (PP) may be used replace some metal materials in gas turbineengines. Currently available PP materials, however, are limitedthermally by commonly employed polymeric substrates. For example,polyethyleneimine (PEI) is not recommended for use at temperaturesexceeding 149° C. (300° F.), which may restrict its applications in gasturbine engines in certain areas of the engine, such as those areas thatare in line-of-sight of a radiant heat source, e.g., the combustor.

However, highly polished metal plated polymer (PP) surface is proposedfor use in gas turbine engines within line-of-sight of radiant heatsources. The highly polished plated metallic layer can significantlyincrease emissivity and thus reduce radiation heating to a componentthat is in line-of-radiation sight with a heat source. Thus, thedisclosed PP materials may be highly polished to expand their use in gasturbine engines.

Thus, plated polymer articles and parts may be highly polished forpurposes of reflecting radiant heat, such as radiant heat emitted from acombustor so that a plated polymer article, part or component may bedisposed within line of sight of a radiant heat source. Further, platedpolymer components may be highly polished for purposes of reducing drag,which is particularly applicable to aerospace applications.

Super-Polished Plated Polymer Articles

Components with very smooth surfaces are desirable in aerospaceapplications to reduce drag. However, metal components, which can bepolished to a very low roughness, are heavy. On the other hand, whilepolymeric substrates are lightweight compared to a metal, polymericsubstrates cannot be polished to a very small surface roughness toreduce drag. Coatings may be applied to a polymer article to reduce thesurface roughness, but they cannot achieve the low surface roughnesspossible with metals.

A disclosed lightweight high-strength super-polished article may becreated by applying typical polishing methods (i.e., grinding, lapping,honing, micromachining, etc.) to a plated polymer article. A disclosedpolished article may include a polymeric substrate 195 and at least onemetallic layer 196 as shown in FIG. 7. The polymeric substrate 195 maybe an injection-molded, compression-molded, blow-molded, additivelymanufactured, or a composite-layup structure formed from at least onepolymer selected from the group consisting of: polyetherimide (PEI);polyimide; polyether ether ketone (PEEK); polyether ketone ketone(PEKK); polysulfone; Nylon; polyphenylsulfide; polyester; and any of theforegoing with fiber reinforcement e.g., carbon-fiber or glass-fibers.An injection molded polymeric substrate may provide a wall thicknessranging from about 0.05 to about 0.25 inches (from about 1270 to about6350 microns), with localized areas ranging up to about 0.5 inches (12.7mm) On the other hand, a compression molded polymeric substrate mayprovide a wall thicknesses ranging from about 0.05 to about 2 inches(from about 1270 microns to about 50.8 mm).

The metallic layer(s) 196 may be applied by electroless plating,electroplating, or electroforming to a thickness ranging from about0.001 to about 0.05 inches (from about 25.4 to about 1270 microns,locally. An average plating thickness may range from about 0.004 toabout 0.04 inches (from about 101.6 to about 1016 microns. Thesethickness ranges may provide resistance to erosion, impact, FOD, etc.and provide the option to finish very aggressively to meet very tighttolerances, surface finish requirements, etc.

The metallic layer(s) 196 may be plated in multiple steps by maskingcertain areas of the polymeric substrate to yield different thicknesses(or no plating) in areas of interest. Such a customized platingthickness profile may also be achieved by tailored racking (includingshields, thieves, conformal anodes, etc.). Such a multiple-step processmay provide for optimization of properties for the polished article withrespect to structural support, etc., without adding undue weight to thepart.

Some mounting features (e.g., flanges or bosses) may be bonded on usinga suitable adhesive after molding but before plating to simplify themold tooling. The polished article may be fabricated in multiplesegments that are joined by conventional processes (e.g., ultrasonic,laser, friction and friction-stir welding; traditional weldingprocesses; adhesives; mitered joints with or without adhesive) beforeplating. The polished article may be produced in multiple components,plated separately and subsequently bonded by transient liquid phase(TLP) bonding. Features such as bosses or inserts may be added (using anadhesive, riveting, etc.) to the article after the plating process.

Thus, plated polymer articles and parts may be highly polished forpurposes of reflecting radiant heat, such as radiant heat emitted from acombustor so that a plated polymer article, part or component may bedisposed within line of sight of a radiant heat source. Further, platedpolymer components may be highly polished for purposes of reducing drag,which is particularly applicable to aerospace applications.

Nacelle Assembly Components

Referring to FIG. 6, the nacelle assembly N presents a number ofadditional opportunities for weight reduction, and therefore a number ofopportunities to incorporate plated polymer parts in accordance withthis disclosure. Specifically, the fan nacelle 134 includes a forwardsegment 190 that may include an aft end 191 that may extend forward froma variable area fan nozzle 192 (VAFN) or thrust reverser doors 203before defining an inlet 193 and fan inlet duct 193 a, beforeterminating at its forward end 194. The forward segment 190 is a largecomponent and, when made from a metal alloy using conventionaltechniques, is quite heavy. The forward segment 190 may be fabricatedfrom a polymeric substrate, a fiber reinforced polymeric substrate or acomposite layup structure as described above that may be plated with oneor more metallic layers.

Referring to FIG. 7, an exemplary component of the fan nacelle 134 mayinclude a polymeric substrate 195 and a metallic layer 196 that maycover both sides of the substrate 195. The substrate 195 may be aninjection-molded, compression-molded, or composite layup piece formed ofat least one of the following: polyetherimide (PEI), polyimide,polyether ether ketone (PEEK), polyether ketone ketone (PEKK),polysulfone, polyamide, polyphenylene sulfide, polyester, polyimide, andcombinations thereof. Suitable thermoset materials may include, but arenot limited to, condensation polyimides, addition polyimides, epoxycured with aliphatic and/or aromatic amines and/or anhydrides, cyanateesters, phenolics, polyesters, polybenzoxazine, polyurethanes,polyacrylates, polymethacrylates, silicones (thermoset), andcombinations thereof. Optionally, the polymeric material of thepolymeric substrate 195 may be structurally reinforced with materialsthat may include carbon, metal, or glass. The fiber-reinforced polymericsubstrate 195 may include a plurality of layers to form a compositelayup structure.

The metallic layer 196 may include one or more layers. The metalliclayer 196 may be applied by electroless plating, electroplating, orelectroforming to a thickness ranging from about 0.001 to about 0.100inches (from about 25 to about 2540 microns), which provides resistanceto erosion, impact, foreign object damage, etc., and the option tofinish aggressively to meet tight tolerances, surface finishrequirements, etc. Plating may be performed in two steps by maskingcertain areas of the segment 190 to yield different thicknesses in areasof interest. Such a customized plating thickness profile can also beachieved by tailored racking (includes shields, thieves, anodes, etc.).In addition, a thicker plated metallic layer 196 allows for moreaggressive machining, finishing, etc. to achieve the desired surfaceroughness, tolerances, etc. Such a multi-step process allows foroptimization of the properties of the fan nacelle 134, with respect tofire, structural support, surface characteristics, etc. without addingundue weight to the segment 190.

The forward segment 190 of the fan nacelle 134 and/or fan inlet duct 193a may be fabricated in multiple segments that are joined by anyconventional process (e.g., ultrasonic, laser, friction, friction-stirwelding; traditional welding processes; adhesive; mitered joint with orwithout adhesive) before plating as discussed above. Furthermore, theforward segment 190 can be produced in multiple segments that are platedseparately and subsequently bonded by transient liquid phase (TLP)bonding. The metallic layer(s) 196 of the forward segment 190 may behighly polished to achieve or promote a laminar flow profile around thenacelle 134.

In addition to the forward segment 190 and fan inlet duct 193 a, otherparts of the fan nacelle 134 or nacelle assembly N can be fabricatedfrom a plated polymer structure. For example, the bulkheads 197, 198,fixed structure 199, thrust reverser doors 203 (only one of two doorsbeing shown in FIG. 6), thrust reverser blocker doors 204 (only one oftwo being shown in FIG. 6), thrust reverser cascades 205, VAFN 192(variable area fan nozzle) and inner cowl may also be fabricated from apolymeric substrate 195 that is coated with a metallic layer 196 asdiscussed above in connection with FIG. 7.

As an alternative shown in FIG. 8, panels capable of sound attenuationmay be fabricated from two plated polymeric substrates 200 prepared inaccordance with the methods discussed above (i.e., a polymeric substrate195 covered with a metallic layer(s) 196) and with a honeycomb layer 201disposed. The honeycomb layer 201 may be fabricated from aluminum, analuminum alloy or another suitable alloy as will be apparent to thoseskilled in the art. The structure of FIG. 8 may be employed for thefixed structure 199, blocker doors 204, the fan nacelle 134 and othercomponents known to those skilled in the art where sound attenuation isdesired.

As shown in FIGS. 9-10, a portion of the forward segment 190 disposed ator near the fan inlet 193 and/or fan inlet duct 193 a (see FIGS. 6 and13A-13B) may include a heating element in the form of a net or mat 202that may be embedded in the substrate 195 c just below the metalliclayer 196 a as shown in FIG. 9. As an alternative, a portion of theforward segment 190 disposed near the fan inlet 193 may include aheating element 202 that is sandwiched between the metallic layer 196 band the substrate 195 d as shown in FIG. 10.

Fan Inlet Duct

The fan inlet duct 193 a of the gas turbine engine 110 of FIG. 6 may beformed from a polymeric substrate 195 and at least one plated metalliclayer 196 as shown in FIG. 7. The exemplary substrate 195 may be aninjection-molded or compression molded article formed from at least onematerial selected from the group consisting of: polyetherimide (PEI),polyimide, polyether ether ketone (PEEK), polyether ketone ketone(PEKK), polysulfone, polyamide, polyphenylene sulfide, polyester,polyimide, and combinations thereof. Suitable thermoset materials mayinclude, but are not limited to, condensation polyimides, additionpolyimides, epoxy cured with aliphatic and/or aromatic amines and/oranhydrides, cyanate esters, phenolics, polyesters, polybenzoxazine,polyurethanes, polyacrylates, polymethacrylates, silicones (thermoset),and combinations thereof. Optionally, the polymeric material of thepolymeric substrate 195 may be structurally reinforced with materialsthat may include carbon, metal, or glass. The fiber-reinforced polymericsubstrate 195 may include a plurality of layers to form a compositelayup structure.

Further, the substrate 195 may be a two-dimensional woven laminatedcomposite that includes carbon fibers or glass fibers in combinationwith an epoxy resin or a similar matrix material. Metal inserts may beincorporated into the substrate 195 to enhance the load-carryingcapability of the resultant structure.

The plated metallic layer 196 may include one or more layers. The platedmetallic layer 196 may be applied by electroless plating,electroplating, or electroforming to a thickness ranging from about0.001 to about 0.03 inches (from about 25.4 to about 762 microns),locally. The average plating thickness may range from about 0.003 toabout 0.025 inches (from about 76.2 to about 635 microns). Thicknesseswithin these ranges provide resistance to erosion, impact, FOD, etc. andthe option to finish more aggressively to meet tight tolerances, surfacefinish requirements, etc. The plated metallic layer 196 may consist ofone or more metals including, but not limited to nickel, cobalt, copper,iron, gold, silver, palladium, rhodium, chromium, zinc, tin, cadmium,and alloys with any of the foregoing elements comprising at least 50 wt.% of the alloy, and combinations thereof.

Plating may be performed in two steps by masking certain areas of theairfoil cluster to yield different thicknesses in areas of interest,such as the cluster platforms. This customized plating thickness profilecan also be achieved by tailored racking (includes shields, thieves,etc.). In addition, a thicker plated metallic layer allows for moreaggressive machining, finishing, etc. to achieve the desired surfaceroughness, tolerances, etc. This multi-step process allows foroptimization of airfoil cluster properties, with respect to fire,structural support, surface characteristics, etc. without adding undueweight to the duct.

More broadly, the fan inlet duct 193 a may be fabricated in multiplesegments that are joined by any conventional process (e.g., ultrasonic,laser, friction, friction-stir welding; traditional welding processes;adhesive; mitered joint with or without adhesive) before plating.Furthermore, components of the fan inlet duct 193 a may be produced andplated separately and subsequently bonded by transient liquid phase(TLP) bonding.

Plated polymer parts offer cost and/or weight savings compared totraditional materials and processes. For example, plating providesbuilt-in erosion protection and superior resistance to loads. Further,additional savings can be realized given the high-throughput ofcurrently available molding and plating processes. Finally, complexgeometries can be accommodated by producing the fan inlet duct 193 a inmultiple polymer segments and joining them together before plating.

Nacelle Bifurcaton—Outer Barrel of Core Nacelle and Inner Barrel of FanNacelle

Turning to FIG. 1, a scheme for connecting the pylon P to the engine 110is shown schematically. As shown in FIG. 11, the fan nacelle 134 and thecore nacelle 112 may each include a pair of generally C-shaped segmentsthat are pivotally coupled together at the pylon P so that the fannacelle 134 and the core nacelle 112 collectively form two pivotallyconnected C-shaped ducts that define the bypass flow path 208. Thoseskilled in the art will appreciate that a multitude of mechanisms forconnecting the engine 110 to the pylon P are available and still fallwithin the spirit and scope of this disclosure.

The pylon P connects the engine 110 to the wing W. During maintenance ofthe engine 110 or its accessories, the C-shaped ducts formed by thebifurcated fan nacelle 134 and core nacelle 112 may be pivoted open in aconventional manner. The pylon P is coupled to the fan nacelle 134 andcore nacelle 112 through an upper bifurcation 209. A lower bifurcation210 provides an opening for the passage of various types of equipmentsuch as electrical lines, hydraulic lines, etc.

To reduce the weight of the fan nacelle 134 and/or core nacelle 112, atleast part of the inner barrel 212 of the fan nacelle 134 and at leastpart of the outer barrel 207 of the core nacelle 112 may be fabricatedusing the disclosed plated polymeric substrates of FIG. 7 in combinationwith an aluminum honeycomb layer 201 as illustrated in FIG. 8. Referringto FIG. 12, the outer fixed structure 207 of the core nacelle 112 mayinclude inner and outer polymeric substrates 195 e, 195 f respectivelythat are plated on either side with metallic layers 196 c, 196 d, 196 e,196 f. The outer substrate 195 f and its respective metallic layers 196e, 196 f may be perforated which, in combination with the honeycombstructure 201, may provide sound attenuation properties. Further, theinner metallic layer 196 c may be coated with an ablative coating 213that faces the interior of the engine core C (FIG. 12) to prevent burnthrough.

The outer fixed structure 207 of the core nacelle 112 providessubstantial weight and cost savings as compared to the prior art, whichteaches a solid aluminum sheet inner wall that is thickly sprayed withan ablative coating. Similarly, the inner barrel 212 of the fan nacelle134 may be fabricated using the structure shown in FIG. 12, without theablative layer 213 or perforations in the outer plated polymer panel.The reduced weight of the polymeric substrates 195 e, 195 f, plusmanufacturing advantages provided by the polymer make the structureshown in FIG. 112 attractive in terms of both cost and weight savings.

In addition, the sprayed ablative layer shown at 213 may be quite heavyand the thickness of the ablative layer is typically set by burn throughtesting. The burn through testing is made more difficult by the use of asolid aluminum inner wall, which is a very good heat conductor. Once theablative is consumed, the aluminum wall conducts the heat to thehoneycomb, which is typically glued in place. Once the glue fails, thehoneycomb will rapidly disbond causing a structural failure. Incontrast, the plated polymeric substrates 195 e, 196 f act as heatinsulators that supplement the ablative coating 213, therebycontributing to the thermal isolation of the glue that holds thehoneycomb layer 201 in place.

Fan Nacelle with Laminar Flow Characteristics and Integrated De-IcingElement

Currently available aluminum inlets for fan nacelles cause turbulentflow of the air as it enters the fan, thereby dramatically increasingdrag. To solve this problem, a plated polymer nacelle 134 a is disclosedin FIGS. 13A-13B and that includes a mirror smooth finish to promotelaminar flow over the outer barrel 253 of the nacelle 134 a as well asthe inlet 193 a. The nacelle 134 a may include outer and inner polymerlayers 195 g, 195 h as shown in FIG. 13B. The outer and inner polymerlayers 195 g, 195 h are plated with metallic layers 196 g, 196 h, 196 i,196 j as shown in FIG. 13B. To provide for laminar flow through theinlet 193 a, the outermost metallic layer 196 g may be polished tomirror smoothness and the inlet 193 a and/or outer barrel 253 may besecured in place without any fasteners at the outer surface. To providefor structural strength at the inlet 193 a for bird strikes and otherincidents, the inner polymer layer 195 h may be thicker than the outerpolymer layer 195 g and/or the metallic layers 196 i, 196 j may bethicker than the metals layers 196 g, 196 h.

Currently available anti-icing systems are too hot for polymerstructures and are usually made of aluminum—an inherently unfriendlysurface for drag reduction through laminar flow. To avoid theseproblems, the inlet 193 a may include a de-icing element in the form ofa conducting layer 254. The conducting layer 254 may include graphiteand may be flexible as well for ease of assembly. The conducting layer254 may be in engagement with the metallic layer 196 h that coats theouter polymer layer 195 g. The thin outer polymer layer 195 g and itsrespective plated metallic layers 196 g, 196 h may be used to conductheat with minimal resistance.

Thus, plated polymers may also be used to construct fan nacelle inletsto promote laminar flow through the nacelle inlets for drag reduction aswell as weight and cost reductions due to the various intricate shapesthat are possible with the disclosed plated polymer systems. Forexample, a disclose fan nacelle inlet may be fabricated from a pair ofplated polymers with a flexible conducting layer sandwichedtherebetween. The outer metallic layer of the outer plated polymer maybe polished to a mirror smoothness to promote laminar flow through thefan nacelle inlet. The conducting layer may be graphite and may be usedfor de-icing as the inner plated metallic layer of the outer platedpolymer may be placed in contact with the conductive layer for purposedof conducting current and heat through the outer plated polymer of thefan nacelle inlet with minimal resistance.

Thin Structures with Tuned Natural Frequencies Achieved by SelectivePlating

Mechanical and structural components, such as automobile parts andaircraft and/or gas turbine engine components are subject to vibration.Vibration generally has the undesirable effect of shortening the servicelife of a component and may result in part or component failures in aworst-case scenario. To mitigate these concerns, such components areoften designed with sufficient mass and stiffness to withstandvibration. As a result, components are often designed to be heavier toshift modes of vibration outside of a critical service region. If acomponent may not be made with a thicker/heavier geometry, then a designor material change must be made to increase the mass or stiffness, whichoften leads to increased costs. Aerospace components (liners, vanes,stators, blades, etc.) also require controlled stiffness, high strength,and low weight. In addition, high fatigue life, impact resistance,load-carrying capability and erosion resistance is required. In the caseof flight-critical components, expensive manufacturing methods areemployed to ensure safety.

To alleviate these problems, a disclosed component may include apolymeric substrate and a plated metallic layer (or plated metalliclayers on either side of the substrate). An exemplary substrate may bean injection-molded, compression-molded, or blow-molded component.Further, an exemplary substrate may be additive manufactured or it maybe a composite-layup structure formed from at least one of thefollowing: polyetherimide (PEI), polyimide, polyether ether ketone(PEEK), polyether ketone ketone (PEKK), polysulfone, polyamide,polyphenylene sulfide, polyester, polyimide, and combinations thereof.Suitable thermoset materials may include, but are not limited to,condensation polyimides, addition polyimides, epoxy cured with aliphaticand/or aromatic amines and/or anhydrides, cyanate esters, phenolics,polyesters, polybenzoxazine, polyurethanes, polyacrylates,polymethacrylates, silicones (thermoset), and combinations thereof.Optionally, the polymeric material of the polymeric substrate 195 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 195 may include aplurality of layers to form a composite layup structure.

Such a composite-layup may be designed in concert with selective platingto achieve a desired overall vibration response. The plated metalliclayer may include one or more layers. The plated metallic layer may beapplied by electroless plating, electroplating, or electroforming andmay have a thickness ranging from about 0.001 to about 0.05 inches (fromabout 25 to about 1270 microns). The average plating thickness may rangefrom about 0.003 to about 0.002 inches (from about 76.2 to about 508microns). This range of thickness may provide resistance to erosion,impact, foreign object damage (FOD), etc. and the option to finish moreaggressively to meet tight tolerances, surface finish requirements, etc.

The plated metallic layer may include one or more layers as discussedabove. Plating may be performed in multiple steps by masking certainareas to yield different thicknesses (or no plating) in areas ofinterest, resulting in a desired vibration response. This customizedplating thickness profile can also be achieved by tailored racking(including shields, thieves, conformal anodes, etc.). This processadditionally allows for optimization of properties for the selectivelytuned component with respect to fire resistance, structural support,surface characteristics, etc., without adding undue weight to thecomponent to completely accommodate each of these properties. Acomponent may also be selectively plated in concert with perforations inorder to act as a vibration dampener as in the case of an engineacoustical liner. Some mounting features (e.g., flanges or bosses) maybe bonded on using a suitable adhesive after molding but before platingto simplify the mold tooling. Selectively tuned components may befabricated in multiple segments that may be joined by conventionalprocesses (e.g., ultrasonic, laser, friction, friction-stir welding;traditional welding processes; adhesives; mitered joints with or withoutadhesive, etc.) before plating as discussed above. Furthermore, theselectively tuned components can be produced and plated separately andsubsequently bonded by transient liquid phase (TLP) bonding. Inaddition, features such as bosses or inserts may be added (using anadhesive, riveting, etc.) to the part after the plating process.Polymeric coatings can also be applied to plated polymer selectivelytuned components to produce a lightweight, stiff, and strong polymerappearing (non-conductive) component. These coatings can be applied byconventional processes, such as spray coating or dip coating, and can beapplied to localized regions only, if desired.

With respect to the molding processes, the polymeric substrate thicknesscan range from about 0.05 to about 0.25 inches (from about 1270 to about6350 microns) using injection molding, with localized areas ranging upto about 0.5 inches (about 1.27 cm). On the other hand, compressionmolding can be used to form polymeric substrate thicknesses ranging upto about 2 inches (about 5.8 cm).

Components made from selectively plated polymeric substrates have theability to control vibration, thereby increasing the useful service lifeof the component and to address any risk of component failure, whichmay, in turn, pose safety risks if the component is an automobile partor an aircraft and/or engine component. The disclosed selectively platedpolymer components may address both primary factors of vibration—massand stiffness variation—across a component. By leveraging this dualcapability to address both the mass and stiffness factors, componentsmay be fabricated with lower weights and/or costs. This is particularlydesirable for aerospace components (liners, vanes, stators, blades,etc.) which require controlled stiffness, high strength, and low weight.Plated polymer components may provide cost and/or weight savingscompared to traditional materials and processes. Schedule savings can berealized given the high-throughput molding and plating processes.Complex and/or large geometries can be accommodated by producingmultiple polymer segments and joining the segments together beforeplating.

Ferro-Magnetic Plated Polymeric Substrates for Housing EMI and EMPGenerating Systems

Electromagnetic interference (EMI) and electromagnetic pulses (EMPs) maybe generated by various electrical and electronic systems such asinduction heads, full authority digital engine controls (FADECs),computers, radios, electrical actuators, etc. For example, radiofrequency emitting induction heads with thermoplastic housings are usedroutinely with other sensitive equipment such as test machine loadframes, linear variable displacement transducers (LVDTs), andextensometers used in fatigue and monotonic testing. Such inductionheads encased in thermoplastic housings release EMI into the environmentwithout any suppression, thereby increasing noise levels for nearbycomponents, such as those listed above. Use of an induction head with athermoplastic housing in conjunction with sensitive electronic andelectrical equipment requires extensive grounding schemes to reduceinterference and noise.

Previous induction heating systems incorporate a metal housing for theinduction head. The metal housing suppresses the radio frequency emittedby the induction head by minimizing the electromagnetic interference.However, metal housings are heavy, thereby adding weight to theinduction heating system. Further, ferrite foils have been used tosuppress EMI, but ferrite foils are obviously not suitable for use inharsh environments where a sturdy housing is required.

As a solution to the problems noted above, plated polymer housings forinduction heads, FADECs, computers, radios, electrical actuators, andother EMI or EMP generating systems. The housings or enclosures may beplated with a ferromagnetic material, i.e., a material that forms apermanent magnet or that is attracted to a magnet. Ferromagneticmaterials that are suitable for plating polymers include nickel, iron,cobalt, and alloys thereof. Suitable alloys include, but are not limitedto nickel-zinc alloys. Other suitable ferromagnetic alloys that may beplated onto a polymeric substrate will be apparent to those skilled inthe art. The use of a ferromagnetic alloy as the plating metal enablesthe plated polymer housing to absorb and thereby significantly reduce oreliminate EMI and/or EMP disturbance to surrounding systems.Additionally, lightweight plated polymer or polymeric substrate housingsor enclosures for electrical and electronic systems such as engineFADECs, computers, and electrical actuators may be used to providesignificant weight reduction opportunities and protection to the systemswithin the plated polymer housings.

Further, plating polymer electronic and electrical housings with aferro-magnetic plating metal will provide lightweight, low-cost EMP andEMI suppression by effectively creating a Faraday cage that isolates thesystems or components disposed within the housing. Sealing features suchas compression, blade, and spring fingers disposed at the housing fayingsurfaces or joints may also be plated to provide electrical continuityand EMP/EMI protection at the housing joints.

By plating thermoplastic or polymeric substrate housings with a thinferromagnetic layer, noise suppression and/or protection may be obtainedwhile low-cost, lightweight thermoplastic housings may still be used.Further, fabricating a component such as an induction head out of aferrite material would be cost prohibitive and would not provide thedurability needed for robust applications.

Cost-effective, robust, and lightweight ferromagnetic-platedthermoplastic or polymeric substrate housings or enclosures aredisclosed. Such housings are useful for electronic and electricalsystems that are sensitive to EMI and EMPs. Further, such housings arealso useful for containing the EMI or EMPs of systems that emit radiofrequencies and that may interfere with neighboring electronic orelectrical systems. For example, induction heads of welding equipmentmay be housed or enclosed in the disclosed plated structures. Further,expensive metal housings for testing instrumentation may be replacedwith the disclosed lower-cost, thermoplastic housings that are platedwith EMI and EMP absorbing material. An added benefit of the disclosedstructures is the enabling of higher instrument sensitivity andmeasurement accuracy because the disclosed housing structures suppressinterfering noise from nearby systems that emit EMI and/or EMPs.

Piston Rods

Hydraulic or pneumatic power may be transferred to a load using a pistonand rod assembly. Such piston and rod assemblies may vary in size,dependent on the amount of force required from the piston in order toperform the desired operation. Piston rods are generally made from ahigh strength metal. When choosing a high strength metal for a pistonrod, a manufacturer often must choose between weight and cost. Forexample, using a lightweight metal such as titanium for a piston roddrastically increases the cost of the piston rod while keeping theweight of the rod low. Conversely, making a piston rod out of aconventional metal like plated steel or stainless steel adds significantweight to the piston rod but keeps the cost of the rod down. As aresult, for weight-sensitive applications, e.g. aerospace, there is aneed for piston rods that are both lightweight and cost-effective.

In satisfaction of this need, an exemplary lightweight plated polymerpiston rod is disclosed. The disclosed rod may include a polymericsubstrate and a metallic layer. The exemplary substrate may be aninjection-molded, compression-molded, blow-molded, additivelymanufactured or composite-layup structure. The polymer may be selectedfrom the group consisting of: polyetherimide (PEI), polyimide, polyetherether ketone (PEEK), polyether ketone ketone (PEKK), polysulfone,polyamide, polyphenylene sulfide, polyester, polyimide, and combinationsthereof. Suitable thermoset materials may include, but are not limitedto, condensation polyimides, addition polyimides, epoxy cured withaliphatic and/or aromatic amines and/or anhydrides, cyanate esters,phenolics, polyesters, polybenzoxazine, polyurethanes, polyacrylates,polymethacrylates, silicones (thermoset), and combinations thereof.Optionally, the polymeric material of the polymeric substrate 195 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 195 may include aplurality of layers to form a composite layup structure.

The metallic layer 196 may include one or more layers. The metalliclayer 196 may be applied by electroless plating, electroplating, orelectroforming to a thickness ranging from about 0.001 to about 0.05inches (from about 25.4 microns to about 1.27 mm), locally. The averageplating thickness may range from about 0.004 to about 0.04 inches (fromabout 101.6 to about 1060 microns). However, in order to increase thestrength of the rod, the plating layer thickness may be increased to anythickness necessary to support the additional strength requirements. The0.004-0.04 inch thickness range may provide resistance to erosion,impact, FOD, etc., and the option to finish more aggressively to meettight tolerances, surface finish requirements, etc. The plating layermay include one or more layers. Plating may be performed in multiplesteps by masking certain areas of the rod to yield different thicknesses(or no plating) in areas of interest. This customized plating thicknessprofile can also be achieved by tailored racking (including shields,thieves, conformal anodes, etc.). This process also allows foroptimization of properties for the disclosed piston rod with respect tofire resistance, structural support, surface characteristics, etc.without adding undue weight to the part to completely accommodate eachof these properties.

To simplify mold tooling, mounting features (e.g., flanges or bosses)may be bonded to the rod after molding, but before plating, using asuitable adhesive. The disclosed lightweight plated polymer piston rodmay be fabricated in multiple segments that are joined before plating bya conventional process, such as: ultrasonic, laser, friction orfriction-stir welding; traditional welding processes; adhesives; miteredjoints, with or without adhesive. Furthermore, the disclosed piston rodmay be produced and plated separately and subsequently bonded bytransient liquid phase (TLP) bonding. In addition, features such asbosses or inserts may be added (using an adhesive, riveting, etc.) tothe part after the plating process.

An injection molded polymeric substrate may have a thickness rangingfrom about 0.05 to about 0.25 inches (from about 1270 to about 6350microns), with localized areas ranging up to about 0.5 inches (about12.7 mm) On the other hand, a compression molded polymeric substrate maybe used to form wall thicknesses ranging from about 0.050 to about 2inches (0.127 to about 5.08 cm). In an embodiment, the polymericsubstrate for the piston rod could be hollow, and filled withhigh-density foam to increase the strength of the rod without addingsubstantially to the weight of the rod.

Turning to FIG. 16, a piston rod 290 is disclosed that includes apolymer tube 291 with an open end 292 that may optionally be filled withhigh density foam prior to applying one of more metallic layers (notshown in FIG. 16). The thickness of metallic layer(s) may be increasedin order to meet the strength requirements of the rod 290. For highweight-bearing rods, the polymer tube 291 may be thin-walled and filledwith high-density foam 293 to increase strength while maintaining a lowweight as illustrated in FIG. 17. One or more metallic layers (notshown) may cover the tube 291 and foam 293. FIGS. 18-19 illustratepiston rods 290 b, 290 c that include polymer tubes 291 that may befilled with a high density foam 293 and closed at the ends 292 withplugs 294, 295 respectively.

As shown in FIG. 18, the plug 294 may be fully received in the end 292of the tube 291 and, as shown in FIG. 19, the plug 295 may be partiallyrecessed into the tube 291. The electroplated or electroless depositedcoatings may include, but are not limited to: nickel, cobalt, copper,iron, gold, silver, palladium, rhodium, chromium, zinc, tin, cadmium,and alloys with any of the foregoing elements comprising at least 50 wt.% of the alloy, and combinations thereof. Plating may be performed inmultiple steps by masking certain areas of the molded article to yielddifferent thicknesses or no plating in certain areas. A customizedplating thickness profile can also be achieved by tailored racking(including shields, thieves, conformal anodes, etc.).

Disclosed piston rods may be formed from a polymeric substrate and oneor more metallic layers. The polymeric substrate may beinjection-molded, compression-molded, blow-molded or additivelymanufactured. The polymeric substrate may also be a composite layupstructure with multiple layers. The polymeric substrate may be formedfrom at least one of the following: polyetherimide (PEI); polyimide;polyether ether ketone (PEEK); polyether ketone ketone (PEKK);polysulfone; polyamide; polyphenylene sulfide; polyester; polyimide; andcombinations thereof. Suitable thermoset materials may include, but arenot limited to: condensation polyimides; addition polyimides; epoxycured with aliphatic and/or aromatic amines and/or anhydrides; cyanateesters; phenolics; polyesters; polybenzoxazine; polyurethanes;polyacrylates; polymethacrylates; silicones (thermoset); andcombinations thereof. Optionally, the polymeric material of thepolymeric substrate 195 may be structurally reinforced with materialsthat may include carbon, metal, or glass. The fiber-reinforced polymericsubstrate 195 may include a plurality of layers to form a compositelayup structure.

The metallic layer(s) 196 may be applied to the polymeric substrate byelectroless plating, electroplating, or electroforming. The resultantinstrument piston rods are strong, lightweight and may be manufacturedusing a variety of techniques with minimal lead-time.

Pump Housings

Pumps used for aircraft engines are typically enclosed in metal housingsor enclosures. A pump typically includes one or more inlets and one ormore outlets to control flow. The metal housings are heavy, therebyadversely affecting fuel consumption. As a result, there is a need forlightweight pump housings for use in aerospace and other applicationswhere weight reduction is a goal.

Lightweight pump housings can be made from plated polymeric substrateswherein the outer plated metallic layer provides a durable andstructural coating. As shown in FIG. 21, an exemplary pump housing maybe fabricated from a polymeric substrate 311 and a metallic layer 312.The substrate 311 may be injection-molded, compression-molded,blow-molded, additively manufactured or a composite-layup structure. Thesubstrate may be formed from at least one polymer selected from thegroup consisting of: polyetherimide (PEI); polyimide; polyether etherketone (PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 311 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 311 may include aplurality of layers to form a composite layup structure.

The metallic layer 312 may include one or more layers. The metalliclayer(s) 312 may be applied by electroless plating, electroplating, orelectroforming to a thickness ranging from about 0.01 to about 0.09inches (from about 254 microns to about 2.29 mm), locally. An averageplating thickness may range from about 0.015 to about 0.08 inches (fromabout 381 microns to about 2.03 mm) These thickness ranges provideresistance to erosion, impact, FOD, etc. and the option to finish moreaggressively to meet tight tolerances, surface finish requirements, etc.The metallic layer 312 may be applied in multiple steps by maskingcertain areas of the pump housing to yield different thicknesses (or noplating) in areas of interest. Such a customized plating thicknessprofile can also be achieved by tailored racking (including shields,thieves, conformal anodes, etc.). This process allows for optimizationof properties for the pump housing with respect to fire resistance,structural support, surface characteristics, etc. without adding undueweight to the pump housing.

Some mounting features (e.g., flanges or bosses) may be bonded on usinga suitable adhesive after molding but before plating to simplify themold tooling. Further, the pump housing may be fabricated in multiplesegments that are joined by any conventional process (e.g., ultrasonic,laser, friction and friction-stir welding processes; traditional weldingprocesses; adhesives; mitered joints with or without adhesive) beforeplating. Furthermore, components of the pump housing may be produced andplated separately and subsequently bonded by transient liquid phase(TLP) bonding. In addition, features such as bosses or inserts may beadded (using an adhesive, riveting, etc.) to the pump housing after theplating process. One or more polymeric coatings 314 may also be appliedto plated polymer pump housing components to produce a lightweight,stiff, and strong polymer appearing (non-conductive) component. Thesecoatings 314 may be applied by conventional processes, such as spraycoating or dip coating.

Plated polymer pump housings offer cost and/or weight savings comparedto traditional metal or thermoplastic pump housings. Further, platedpolymer pump housings provide reduced manufacturing costs due to thehigh-throughput molding and plating processes used to fabricated theplated polymer pump housings. Pump housings with complex geometries canbe accommodated by producing multiple polymer segments and joining thesegments together before plating to simplify the mold tooling.Alternatively, the segments can be plated separately and subsequentlyjoined using TLP.

Instrumentation Probes

Instrumentation probes may be utilized to locate and attachinstrumentation needed to assess actual performance of an engine ordevice, e.g., a gas turbine engine. Instrumentation probes need to fitinto limited available spaces and be physically attached in a stable andsecure manner. Because instrumentation probes are used to troubleshootproblems associated with engines and devices that are in service, theyoften need to be fabricated within a relatively short lead-time.

Turning to FIG. 20, a disclosed instrumentation probe 300 may include apolymeric substrate 301 coated with one or more metallic layers 302. Thepolymeric substrate 301 may be an injection-molded, compression-molded,blow-molded or additively manufactured component. The polymericsubstrate 301 may also be composite-layup structure with multiple layersshown schematically at 303. The polymeric substrate 301 may be formedfrom at least one of the following: polyetherimide (PEI); polyimide;polyether ether ketone (PEEK); polyether ketone ketone (PEKK);polysulfone; polyamide; polyphenylene sulfide; polyester; polyimide; andcombinations thereof. Suitable thermoset materials may include, but arenot limited to: condensation polyimides; addition polyimides; epoxycured with aliphatic and/or aromatic amines and/or anhydrides; cyanateesters; phenolics; polyesters; polybenzoxazine; polyurethanes;polyacrylates; polymethacrylates; silicones (thermoset); andcombinations thereof. The metallic layer(s) 302 may be applied byelectroless plating, electroplating, or electroforming and may have athickness ranging from about 0.0001 to about 0.03 inches (from about2.54 to about 762 microns, locally. The average thickness of themetallic layer(s) 302 may range from about 0.001 to about 0.02 inches(from about 25.4 to about 508 microns). These thickness ranges provideresistance to erosion, impact, FOD, etc. and the option to finish moreaggressively to meet tight tolerances, surface finish requirements, etc.

The metallic layer(s) 302 may be plated in multiple steps by maskingcertain areas of the polymeric substrate to yield different thicknesses(or no plating) in areas of interest. Such a customized platingthickness profile may also be achieved by tailored racking (includingshields, thieves, conformal anodes, etc.). Tailored racking may allowfor optimization of properties for the instrumentation probe 300 withrespect to structural support, surface characteristics, etc. withoutadding undue weight to the probe 300.

Further, some mounting features (e.g., flanges or bosses) may be bondedto the polymeric substrate using a suitable adhesive after molding butbefore plating to simplify the mold tooling. More broadly, theinstrumentation probe may be fabricated in multiple segments beforeplating that are joined by any conventional process (e.g., ultrasonic,laser, friction and friction-stir welding processes; traditional weldingprocesses; adhesives; mitered joints with or without adhesives).Furthermore, the instrumentation probe 300 may be molded as separatesegments, plated separately and the plated segments may be subsequentlybonded by transient liquid phase (TLP) bonding. In addition, featuressuch as bosses or inserts may be added (using an adhesive, riveting,etc.) to the plated polymeric substrate or probe after the platingprocess. One or more polymeric coatings 304 may also be applied to theplated polymer instrumentation probe 300 to provide a lightweight, stiffand strong probe with a polymeric coating 304 or appearance. Suchpolymeric coatings 304 may be applied by conventional processes, such asspray coating or dip coating, and may be applied to localized areas.

Thus, disclosed instrument probes may be formed from a polymericsubstrate and one or more metallic layers. The polymeric substrate maybe injection-molded, compression-molded, blow-molded or additivelymanufactured. The polymeric substrate may also be a composite layupstructure with multiple layers of one or more polymeric materialsrecited above. The metallic layer(s) may be applied to the polymericsubstrate by electroless plating, electroplating, or electroforming. Theresultant instrument probes are strong, lightweight and may bemanufactured using a variety of techniques with minimal lead-time.

Waveguides

A waveguide is a structure that guides energy, such as microwave,optical, electromagnetic, acoustic, etc. Some uses for waveguidesinclude the transmission of power between components of a system.Waveguides are also used as a fundamental method of non-destructivetesting. The geometry of the waveguide controls the effectiveness of thewaveguide structure, and in some cases, the geometry of the waveguidemay be complex. Further, many applications require waveguides to belightweight, stiff and/or strong. For example, structural rigidity isneeded as it partially controls the energy transmission efficiency ofthe waveguide. In addition, typically, low costs and manufacturabilityare primary concerns.

Turning to FIG. 21, one disclosed waveguide 310 may include a polymericsubstrate 311 and one or more metallic layers 312. The polymericsubstrate 311 may be injection-molded, compression-molded, blow-moldedor additively manufactured. The polymeric substrate 311 may also be acomposite layup structure with multiple layers shown schematically at313. The polymeric substrate 311 may be formed from at least one of thefollowing: polyetherimide (PEI); polyimide; polyether ether ketone(PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof. Themetallic layer(s) 312 may be applied to the polymeric substrate 311 byelectroless plating, electroplating, or electroforming to a thicknessranging from about 0.001 to about 0.100 inches (from about 2.54 to about2540 microns, locally. The average plating thickness may range fromabout 0.0005 to about 0.05 inches (from about 12.7 to about 1270microns). These thicknesses provide resistance to erosion, impact, FOD,etc. and the option to finish more aggressively to meet tighttolerances, surface finish requirements, etc.

As noted above, the metallic layer(s) 312 may be plated in multiplesteps by masking certain areas of the waveguide to yield differentthicknesses (or no plating) in areas of interest. Such a customizedplating thickness profile may also be achieved by tailored racking(including shields, thieves, conformal anodes, etc.). Tailored rackingmay be used to optimize propertied of the waveguide with respect to fireresistance, structural support, surface characteristics, etc., withoutadding undue weight to the part to the waveguide.

Some mounting features (e.g., flanges or bosses) may be bonded to themolded polymeric substrate 311 using a suitable adhesive after moldingbut before plating to simplify the mold tooling. Further, the waveguide310 may be fabricated or molded in multiple segments that are joinedafter molding and before plating by a conventional process (e.g.,ultrasonic, laser, friction or friction-stir welding processes;traditional welding processes; adhesives; mitered joints with or withoutadhesive, etc.). Furthermore, the polymeric substrate 311 may be moldedas separate segments, plated separately and the plated polymer segmentsmay be subsequently bonded by transient liquid phase (TLP) bonding.Features such as bosses or inserts may be added (using an adhesive,riveting, etc.) to the plated polymeric substrate 311 after the platingprocess. One or more polymeric coatings 314 may be applied to platedpolymeric substrate or waveguide 310 to produce a lightweight, stiff,and strong waveguide 310 with a polymer appearance. Such polymericcoatings 314 may be applied by conventional processes, such as spraycoating or dip coating, and can be applied to localized regions only, ifdesired.

With respect to the molding processes, an injection molded polymericsubstrate 311 may have a thickness ranging from about 0.05 to about 0.25inches (from about 1270 to about 6350 microns), with localized areasranging up to about 0.5 inches (12.7 mm) On the other hand, acompression molded polymeric substrate 311 may be formed with athicknesses ranging from about 0.05 to about 2 inches (from about 1270microns to about 50.8 mm).

Disclosed waveguides may be formed from a polymeric substrate and one ormore metallic layers. The polymeric substrate may be injection-molded,compression-molded, blow-molded or additively manufactured. Thepolymeric substrate may also be a composite layup structure withmultiple layers. The polymeric substrate may be formed from at least oneof the following: polyetherimide (PEI); polyimide; polyether etherketone (PEEK); polyether ketone ketone (PEKK); polysulfone; Nylon;polyphenylsulfide; polyester; and any of the foregoing with fiberreinforcement e.g., carbon-fiber or glass-fibers. The metallic layer(s)may be applied to the polymeric substrate by electroless plating,electroplating, or electroforming. The resultant waveguides are strong,lightweight and may be manufactured using a variety of techniques withminimal lead-time.

Heat Exchangers

Heat exchangers are currently produced using alloys with high thermalconductivity such as copper. Heat exchangers are also typicallyconstructed in two major forms (plate fin or shell and tube). Modernheat exchangers must be assembled using techniques such as brazing,welding, or extrusion/press fit between mating parts. For aerospace,automotive and other payload sensitive applications, the weight of aheat exchanger assembly is a major design driver. Furthermore, jointsand sealing surfaces between hot and cold sides of a heat exchanger areprone to leakage, which compromises the cooling effectiveness of theheat exchanger. Accordingly, methods for producing a lightweight, highcooling effectiveness heat exchanger would have significant utility andcommercial value.

Disclosed herein are heat exchangers and components of heat exchangersmade from plated polymeric substrates 310 or polymeric substrates 311that are molded or otherwise formed into a desired shape before they areplated with one or more metallic layers 312 as shown in FIG. 21. Usefulpolymeric substrates 311 may be injection-molded, compression-molded,extrusion-molded or additive-manufactured. An injection molded polymericsubstrate 311 may provide a wall thickness ranging from about 0.05 toabout 0.25 inches (from about 1270 to about 6350 microns) with localizedareas ranging up to about 0.5 inches (about 12.7 mm) On the other hand,a compression molded polymeric substrate 311 may provide a wallthickness ranging from about 0.05 to about 2 inches (from about 1.27 toabout 50.8 mm) The polymeric substrates 311 may be fabricated using atleast one polymer selected from the group consisting of: polyetherimide(PEI); polyimide; polyether ether ketone (PEEK); polyether ketone ketone(PEKK); polysulfone; polyamide; polyphenylene sulfide; polyester;polyimide; and combinations thereof. Suitable thermoset materials mayinclude, but are not limited to: condensation polyimides; additionpolyimides; epoxy cured with aliphatic and/or aromatic amines and/oranhydrides; cyanate esters; phenolics; polyesters; polybenzoxazine;polyurethanes; polyacrylates; polymethacrylates; silicones (thermoset);and combinations thereof. Passages may be formed in the polymericsubstrate(s) using conventional methods (e.g., washed-out mandrels,machining, etc.).

The metallic layer(s) 312 may be applied by electroless plating,electroplating, or electroforming to a thickness ranging from about0.001 to about 0.03 inches (from about 25.4 to about 762 microns),locally. An average plating thickness may range from about 0.001 toabout 0.02 inches (from about 25.4 to about 508 microns). Thesethickness ranges provide resistance to erosion, impact, FOD, etc., andthe option to finish more aggressively to meet tight tolerances, surfacefinish requirements, etc. The metallic layer(s) may be plated inmultiple steps by masking certain areas of the substrate 311 to yielddifferent thicknesses in areas of interest. Such a customized platingthickness profile may also be achieved by tailored racking (includingshields, thieves, conformal anodes, etc.). Further, a thicker metalliclayer 312 allows for more aggressive machining, finishing, etc. toachieve the desired surface roughness, tolerances, etc. Thismultiple-step process allows for optimization of properties for the heatexchanger or heat exchanger component with respect to fire, structuralsupport, surface characteristics, etc., without adding undue weight tothe part.

Some mounting features (e.g., flanges, bosses, etc.) may be bonded tothe polymeric substrate 311 using a suitable adhesive after molding, butbefore plating, to simplify the mold tooling. The plates, fins, shells,tubes, fittings and cover parts of a heat exchanger may be fabricated inmultiple segments, which may be joined by conventional processes (e.g.,ultrasonic, laser, friction and friction-stir welding processes;traditional welding processes; adhesives; mitered joints with or withoutadhesive) before plating. Because the metallic layer 312 is thick enoughto provide significant structural strength and rigidity, the method ofjoining the segments of polymeric substrate 311 will likely not limitthe strength of the finished component. Furthermore, the plates, fins,shells, tubes, fittings and cover parts may be molded, plated separatelyand subsequently bonded together by transient liquid phase (TLP)bonding. In addition, features such as bosses or inserts may be added(using an adhesive, riveting, etc.) to the component or assembly afterthe plating process.

Reduced-weight heat exchangers are disclosed that may be fabricated fromplated polymers or plated polymeric substrates. The disclosedmanufacturing methods provide flexibility in the design of heatexchangers, especially when using additive manufacturing to create thepolymeric substrate(s). Manufacturing savings may be realized given thedisclosed high-throughput molding and plating processes used tofabricated the disclosed heat exchangers. Complex geometries can beaccommodated by producing multiple polymer segments and joining themtogether before plating.

LPC Made from Plated Polyermic Substrates

Geared turbofan (GTF) engines and other advanced aero-engines couldbenefit from weight reducing technologies to improve overall engine fuelburn for flight cycles. Turning to FIG. 1, in a geared turbofan (GTF)engine 110, the low-pressure compressor (LPC) 116 assumes a greaterpercentage of the total work in compressing the engine core airflow thanthe high-pressure compressor (HPC) 126. The LPC 116 is also disposedopposite the combustor 130 from the HPC 126.

Plated polymers are disclosed herein for use in the manufacture of theLPC 116 that include a polymeric substrate 311 plated with one or moremetallic layer 312 as shown in FIG. 21. Turning to FIG. 22, anindividual stage 320 of the LPC 116 is partially shown. Each stage 320includes a hub 321 connected to an airfoil 322. The airfoil 322 includesa leading end 323 and a trailing end 324. Each stage 320 may bemanufactured separately and bonded together either before or after thepolymeric substrate 311 is plated with one or more metallic layers 312.Alternatively, each stage 320 of the LPC 116 may be constructedseparately and bound together using a tie shaft form of construction asillustrated in US20110219784. The polymeric substrate 311 may beselected based on the operating temperature expected for each stage ofthe flow path through the LPC 116. The downstream stages of the LPC 116may require higher operating temperatures and therefore polymers such aspolyimides may be used due to the proximity of the downstream stages tothe combustor 130. In contrast, the upstream stages of the LPC 116 maybe fabricated from polymers that are less sensitive to high operatingtemperatures because the upstream stages are farther away from thecombustor 130. The polymeric substrates may also be strengthened via theintroduction of continuous or discontinuous fiber reinforcements. Inorder to fully accommodate wear, strength, and durability requirementsfor each LPC stage 320, each stage 320 may be plated a metallic layer312.

Useful polymeric substrates 311 may be injection-molded,compression-molded, extrusion-molded or additive-manufactured. Aninjection molded polymeric substrate 311 may provide a wall thicknessranging from about 0.05 to about 0.25 inches (from about 1270 to about6350 microns), with localized areas ranging up to about 0.5 inches(about 12.7 mm) On the other hand, a compression molded polymericsubstrate 311 may provide a wall thickness ranging from about 0.05 toabout 2 inches (from about 1270 microns to about 50.8 mm) The polymericsubstrates 311 may be fabricated using at least one polymer selectedfrom the group consisting of: polyetherimide (PEI); polyimide; polyetherether ketone (PEEK); polyether ketone ketone (PEKK); polysulfone; Nylon;polyphenylsulfide; polyester; and any of the foregoing with fiberreinforcement e.g., carbon-fiber or glass-fibers. Passages may be formedin the polymeric substrate(s) using conventional methods (e.g.,washed-out mandrels, machining, etc.).

The metallic layer 312 may be applied by electroplating, electrolessplating, brush plating, spray metal deposition, or a powder spray metalprocess. The thickness of the metallic layer may range from about 0.005to about 0.1 inches (from about 127 microns to about 2.54 mm) Forrelatively thick metallic layers 312, a secondary machining or abrasivegrinding operation may be performed to shape the trailing edge 324 (FIG.22) to a minimal practical thickness. Further, the metallic layer 312need not be of a uniform thickness. For example, with respect to thevanes or airfoils 322 of the LPC 116, the metallic layer 312 may be thinin the forward or leading edge region 323 of the airfoil 322 and thickerin the trailing edge region or aft region 324 of the airfoil 322. Thenon-uniform thickness may be achieved by known processing techniques.

The metallic layer(s) 312 may be applied by electroless plating,electroplating or electroforming to a thickness ranging from about 0.001to about 0.03 inches (from about 25.4 to about 762 microns), locally. Anaverage plating thickness may range from about 0.001 to about 0.02inches (from about 25.4 to about 508 microns). These thickness rangesprovide resistance to erosion, impact, FOD, etc., and the option tofinish more aggressively to meet tight tolerances, surface finishrequirements, etc. The metallic layer(s) 312 may be plated in multiplesteps by masking certain areas of the substrate 311 to yield differentthicknesses in areas of interest. Such a customized plating thicknessprofile may also be achieved by tailored racking (including shields,thieves, conformal anodes, etc.). Further, a thicker metallic layer 312allows for more aggressive machining, finishing, etc. to achieve thedesired surface roughness, tolerances, etc. This multiple-step processallows for optimization of properties for the LPC stage 320 with respectto fire, structural support, surface characteristics, etc., withoutadding undue weight to the stage 320.

Some mounting features (e.g., flanges, bosses, etc.) may be bonded tothe polymeric substrate 311 using a suitable adhesive after molding, butbefore plating, to simplify the mold tooling. As noted above, the stages320 may be fabricated separately and in multiple segments, which may bejoined by conventional processes (e.g., ultrasonic, laser, friction andfriction-stir welding processes; traditional welding processes;adhesives; mitered joints with or without adhesive) before plating.Because the metallic layer 312 is thick enough to provide significantstructural strength and rigidity, the method of joining the segments ofpolymeric substrate 311 will likely not limit the strength of thefinished stage 320. In addition, features such as bosses or inserts maybe added (using an adhesive, riveting, etc.) to the stage 320 or to theLPC 116 after the plating process.

The metallic layer 312 may be applied by electroplating, electrolessplating, brush plating, spray metal deposition, or a powder spray metalprocess. The thickness of the metallic layer may range from about 0.005to about 0.100 inches (from about 127 microns to about 2.54 mm) Forrelatively thick metallic layers 312, a secondary machining or abrasivegrinding operation may be performed to shape the trailing edge 324 (FIG.22) to a minimal practical thickness. Further, the metallic layer 312need not be of a uniform thickness. For example, with respect to thevanes or airfoils 322 of the LPC 116, the metallic layer 312 may be thinin the forward or leading edge region 323 of the airfoil 322 and thickerin the trailing edge region or aft region 324 of the airfoil 322. Thenon-uniform thickness may be achieved by known processing techniques.

The techniques described herein will enable lighter LPC components forany gas turbine engine because current LPCs are made of aluminum. Aplated polymer LPC or LPC component that is plated with higher hardnessand toughness materials such as nickel will improve compressordurability, especially for GTF engines where higher percentages of totalcompression work is performed in the LPC.

Grounding Strips

Some aerospace components must have conductive paths to groundelectricity that is induced by events such as lightning strikes. Staticelectricity may also be dissipated in this manner. While polymer andcomposite parts are being used to replace parts on airplanes to saveweight, fuel and manufacturing costs, polymers and composites are notinherently conductive materials. Some such polymer, composite orotherwise non-conductive parts or components must include a conductivepath for grounding purposes. Otherwise, a lightning strike or thebuild-up of static electricity can have serious detrimental consequenceson non-grounded components made of these lightweight non-metalmaterials.

As a solution to this problem, a polymer component 330 is disclosed inFIG. 23 the includes a molded polymeric substrate 331 that isselectively plated with a metallic layer 332. The non-coated side 333 ofthe substrate 331 may be masked to limit the metallic layer 332 to theopposite side 334 of the substrate 331. As a result, a lightweight andlow-cost grounding strip is provided by the metallic layer 332 forgrounding the polymer component 330. Using the disclosed masking ofpolymer components 330, a customized grounding network may be producedto help optimize the component's grounding capability.

The exemplary polymeric substrate may be injection-molded,compression-molded, blow-molded, additively manufactured or acomposite-layup structure. The polymeric substrate may be formed from atleast one of the following polymers selected from the group consistingof: polyetherimide (PEI); polyimide; polyether ether ketone (PEEK);polyether ketone ketone (PEKK); polysulfone; polyamide; polyphenylenesulfide; polyester; polyimide; and combinations thereof. Suitablethermoset materials may include, but are not limited to: condensationpolyimides; addition polyimides; epoxy cured with aliphatic and/oraromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.

In addition to the selective surface plating approach described above,recesses or pockets can be machined in the polymeric substrate 331 orprovided in the forming process (molding, build file) of the polymericsubstrate 331 to provide for an even surface between the polymer andplating strips or metallic layers 332 to prevent increased drag or(increased) turbulence. The use of such recesses or pockets facilitatesthe masking of the polymeric substrate 331 for the plating process. Thegrounding strips or metallic layers 332 may include one or more metalsincluding, but not limited to: nickel; cobalt; copper; iron; gold;silver; palladium; rhodium; chromium; zinc; tin; cadmium; and alloyswith any of the foregoing elements comprising at least 50 wt. % of thealloy; and combinations thereof. Plating may be performed in multiplesteps by masking certain areas of the molded article to yield differentthicknesses or no plating in certain areas. A customized platingthickness profile can also be achieved by tailored racking (includingshields, thieves, conformal anodes, etc.).

A lightweight solution to lightning-strike grounding is provided in theform of plated grounding strips on molded polymer components. Thegrounding strips may be selectively plated onto a molded polymer articleor component by masking areas of the article. The selective platingprocess is applicable to composite nacelles and other components thatcould be fabricated from polymer or composite materials, such as fanblades, fan cases, guide vanes, splitters, etc.

Plated Polymer Ducts

In a gas turbine engine, ducting can be fabricated using a variety ofprocesses, such as a composite layup or forming sheet metal to thedesired shape using a combination of cutting, bending, welding, and/orstamping processes. These processes tend to be expensive and/or timeconsuming.

Disclosed plated polymer ducts may include a polymeric substrate and ametallic layer that replaces either a sheet metal part or a compositelayup baseline part. As shown in FIG. 26, a disclosed duct 350 extendsfrom an inlet end formed at a flange 351 to an outlet end formed at aflange 352. One or both of the flanges 351, 352 may include mountingholes 353 as shown in FIG. 26. Additionally, the duct 350 may includeports and/or integral fittings and/or further mounting features that arenot shown in FIG. 26.

The metallic layer 354 and the polymeric substrate 355 each may includeone or more layers. The metallic layer 354 may be plated onto thepolymer layer 355 in multiple steps by masking certain areas of the duct350 to yield different thicknesses in areas of interest. For example, athicker metallic layer 354 can be provided on the inside surface 356 oralong the flow path of the duct 350 for structural integrity during anexternal fire. In addition, a thicker metallic layer 354 allows for moreaggressive machining, finishing, etc. to achieve the desired surfaceroughness, tolerances, etc. This multi-step plating process allows foroptimization of duct properties, with respect to fire, structuralsupport, surface characteristics, etc. without adding undue weight tothe duct 350.

The exemplary substrate 355 is injection-molded or compression moldedand may be formed from at least one of the following: may include, butare not limited to: polyetherimide (PEI); polyimide; polyether etherketone (PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 195 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 195 may include aplurality of layers to form a composite layup structure.

Some mounting features (e.g., flanges or bosses) may be bonded to thesubstrate 355 using a suitable adhesive after molding but before platingto simplify the mold tooling. Further, the duct 350 may be fabricated inmultiple segments that are joined by any conventional process (e.g.,ultrasonic, laser, friction or friction-stir welding processes;traditional welding processes; adhesives; mitered joints with or withoutadhesive) before plating. Because the metallic layer(s) 354 is thickenough to provide significant structural strength and rigidity, themethod of joining segments will likely not be a strength limiter. Inaddition, features such as bosses or inserts may be added (using anadhesive, riveting, etc.) to the duct 350 after the plating process.Furthermore, the duct may be produced in a plurality of segments thatare plated separately and subsequently bonded by transient liquid phase(TLP) bonding.

The polymeric substrate 355 may have a wall thickness ranging from about0.05 to about 0.25 inches (from about 1.27 to about 6.35 mm), withlocalized areas ranging up to about 0.5 inches (12.7 mm) forinjection-molded substrates 355. On the other hand, a compression-moldedsubstrate 355 may have a wall thicknesses ranging from about 0.05 toabout 2 inches (from about 1.27 to about 50.8 mm).

Portions of the metallic layer 354 may be purposefully weakened (or thepolymeric substrate can be masked before plating) to provide paths foroutgassing and expansion of the polymeric substrate 355 during a fire.These portions should not reside near areas of the duct 350 that aresignificantly stressed or that are stress concentrations and may bemasked areas, scored lines, a few large holes, many smaller holes, etc.to provide appropriate redirection of thermally induced stresses andstrains away from critical load paths.

The metallic layer 354 may be applied by electroless plating,electroplating, or electroforming to a thickness ranging from about0.002 to about 1270 microns (from about 50.8 to about 1270 microns). Themetallic layer 354 may be any one or more of: nickel; cobalt; copper;iron; gold; silver; palladium; rhodium; chromium; zinc; tin; cadmium;and alloys with any of the foregoing elements comprising at least 50 wt.% of the alloy; and combinations thereof. Plating may be performed inmultiple steps by masking certain areas of the molded article to yielddifferent thicknesses or no plating in certain areas. A customizedplating thickness profile can also be achieved by tailored racking(including shields, thieves, conformal anodes, etc.).

Plated polymer ducts for gas turbine engines offer cost and/or weightsavings compared to composite layup or sheet metal parts. Injectionmolding and plating processes provide faster and easier manufacturing ofgas turbine engine ducts. Complex geometries can be accommodated byproducing the ducts in multiple polymer segments and joining themtogether before or after plating.

Plated Polymer Fan Platforms

A fan platform is a rotating part that defines the flow path between fanblades during normal operation of a turbofan gas turbine engine. Fanplatforms must maintain sufficient structural integrity after a birdstrike or fan blade-out event to preserve the rotation of the fan bladesof a fan blade assembly to meet minimum thrust and/or shutdownrequirements as required by FAA regulations.

Turning to FIG. 27, an exemplary fan platform 360 is shown that may bedisposed between adjacent fan blades, one of which is shown in atruncated form at 361 in FIG. 27. Each fan platform 360 may include abody 362 that defines a radially outwardly flow path surface 363. Theflow path surface 363 defines a substantially aerodynamic flow pathsurface for airflow between adjacent fan blades 361. The fan platform360 may be formed from a polymeric substrate 311 that is at leastpartially coated with at least one metallic layer 312 as shown in FIG.21. The fan platform 360 may replace prior art platforms that arefabricated from composite layup structures, aluminum, or titanium. Thedisclosed fan platform 360 may include integral fittings and/or mountingfeatures. The metallic layer 312 may include one or more layers. Platingmay be performed in multiple steps by masking certain areas of theplatform 360 to yield different thicknesses in areas of interest. Forexample, a thicker metallic layer 312 on the inside of mounting featuresmay provide structural integrity. In addition, a thicker metallic layer312 allows for more aggressive machining, finishing, etc., to achievethe desired surface roughness, tolerances, etc. in certain locations ofthe platform 360. This multi-step plating process allows foroptimization of platform properties with respect to structural support,surface characteristics, etc. without adding undue weight to theplatform 360.

The exemplary substrate 311 may be injection-molded or compressionmolded and may be formed of at least one polymer selected from the groupconsisting of: polyetherimide (PEI); polyimide; polyether ether ketone(PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 311 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 311 may include aplurality of layers to form a composite layup structure.

Some mounting features (e.g., flanges or bosses) may be to the substrate311 using suitable adhesives after molding but before plating tosimplify the mold tooling. The platform may also be fabricated inmultiple segments that are joined by a conventional process (e.g.,ultrasonic, laser, friction and friction-stir welding processes;traditional welding processes; adhesives; mitered joints with or withoutadhesives) and before plating. It is possible to use a metallic layer312 thick enough to provide significant structural strength and rigiditysuch that the method of joining segments will likely not be a strengthlimiter. Furthermore, the platform may be produced in a plurality ofsegments that are plated separately and subsequently bonded by transientliquid phase (TLP) bonding.

An injection molded polymeric substrate 311 may have a wall thicknessranging from about 0.05 inch (1.27 mm) to about 0.2 inches (5.08 mm) Acompression-molded substrate 311 may have a wall thickness ranging from0.05 inch (1.27 mm) to about 2 inches (5.08 cm). The metallic layer 312may be applied by electroless plating, electroplating or electroformingto a thickness ranging from about 0.004 to about 0.025 inches (fromabout 102 to about 635 microns).

Plated polymer fan platforms may provide cost savings in comparison tofan platforms made from composite layup structures, aluminum, ortitanium. The metallic layer 312 provides built-in erosion protectionand structural integrity.

Plating as a Method of Forming Endwall Contours

End walls (platforms) of advanced gas turbine engine airfoils havethree-dimensional (3D) contours in order to reduce vortex flow throughthe engine. 3D contoured end walls are difficult and costly tofabricate.

As shown in FIG. 28, rotating airfoils 371 are supported on platforms370. Each platform 370 includes a radially outwardly facing end wall372. The end walls 372 may be three-dimensional or contoured, whichmakes them difficult and costly to manufacture. To address this problem,the plating technology disclosed herein provides the ability to producemetal plated polymer layers of variable thicknesses. Referring to FIGS.21 and 28, the disclosed technology allows selectively thicker andthinner regions of the plated metallic layer(s) 312 over the surface ofthe polymeric substrate 311 (FIG. 21) that, together with the metalliclayer(s) 312 to form the end wall 372 (FIG. 28). The thickness of themetallic layer(s) 312 may be controlled by adjusting process parameters,adjusting plating racking and fixturing, and over plating the end wallfollowed by post-machining processes.

The thickness of the metallic layer(s) 312 may selectively be increasedto form contours in the end wall 372 form a two-dimensional axisymmetricpart. The method may include using traditional manufacturing technology,such as but not limited to, casting, forging, injection molding,compression molding, to create an airfoil end wall having no 3D contours(2D axisymmetric). The method may also include plating the 3D contourson top of the end wall 372 by way of selectively plating certain regionswith a greater thickness than another region. The method may furtherinclude polishing the plated 3D contours to achieve desired finalcontour and flow path surface finish.

An exemplary polymeric substrate 311 may be injection-molded orcompression molded and may include one or more polymers selected fromthe group consisting of: polyetherimide (PEI); polyimide; polyetherether ketone (PEEK); polyether ketone ketone (PEKK); polysulfone;polyamide; polyphenylene sulfide; polyester; polyimide; and combinationsthereof. Suitable thermoset materials may include, but are not limitedto: condensation polyimides; addition polyimides; epoxy cured withaliphatic and/or aromatic amines and/or anhydrides; cyanate esters;phenolics; polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.

The metallic layer 312 may then be applied to the polymeric substrate311 by methods including, but not limited to, electroless plating,electroplating, or electroforming. The metallic layer 311 may be anynumber of different metals or alloys including, but not limited to:nickel; cobalt; copper; iron; gold; silver; palladium; rhodium;chromium; zinc; tin; cadmium; and alloys with any of the foregoingelements comprising at least 50 wt. % of the alloy; and combinationsthereof. Plating may be performed in multiple steps by masking certainareas of the molded article to yield different thicknesses or no platingin certain areas. A customized plating thickness profile can also beachieved by tailored racking (including shields, thieves, conformalanodes, etc.). The metallic layer 312 may be polished after plating toprovide at least two benefits. First, a highly polished metallic layer312 with have a high emissivity and therefore will be less subject toheating by radiant heat sources. Further, a highly polished metalliclayer 312 will have improved smoothness, thereby promoting laminar flowand increased turbine and compressor efficiencies.

Thus, the disclosed plated polymer technology provides an affordableapproach to forming 3D contours in platform end walls. Further,polishing the metallic layer surface increases emissivity and thusreduces heating of the platform by thermal radiation. A polishedmetallic layer surface also improves the gas flow path smoothnesstranslating to gas turbine engine efficiency. A molded polymericsubstrate and may be used as a fast, durable prototyping method tocreate 3D contours for end wall a similar 2D prototype, without the needfor expensive hard tooling, or long lead time machining.

Fadec Housings

Full authority digital controls (FADECs) are used to house the enginecontrol unit on aircraft engines. FADECs control all engine functionsand communicate with the aircraft controls to ensure safe operation.FADEC housings are traditionally fabricated from aluminum castings,which are affordable but heavy. A lighter-weight more affordable FADEC(or any electrical control unit) housing could benefit any industrywhere weight versus payload and cost are design considerations (e.g.,marine vehicle controls, automotive controls, etc.).

Referring to FIG. 21, an exemplary electrical control unit housingcomprises a polymeric substrate 311 and a metallic layer 312. Theexemplary substrate 311 may be injection-molded, compression-molded,blow-molded, additively manufactured or a composite layup structureformed from one or more of the following: polyetherimide (PEI);polyimide; polyether ether ketone (PEEK); polyether ketone ketone(PEKK); polysulfone; polyamide; polyphenylene sulfide; polyester;polyimide; and combinations thereof. Suitable thermoset materials mayinclude, but are not limited to: condensation polyimides; additionpolyimides; epoxy cured with aliphatic and/or aromatic amines and/oranhydrides; cyanate esters; phenolics; polyesters; polybenzoxazine;polyurethanes; polyacrylates; polymethacrylates; silicones (thermoset);and combinations thereof. Optionally, the polymeric material of thepolymeric substrate 311 may be structurally reinforced with materialsthat may include carbon, metal, or glass. The fiber-reinforced polymericsubstrate 311 may include a plurality of layers to form a compositelayup structure. The polymeric substrate 311 may be fabricated around asuitable core to serve as an in situ mandrel and to provide the correctstructural and electrical shielding characteristics for anelectrical/electronic control unit.

The metallic layer(s) 312 may be applied by electroless plating,electroplating, or electroforming to a uniform thickness ranging fromabout 0.001 to about 0.05 inch (from about 25.4 microns to about 1.27mm) The average plating thickness may range from about 0.003 to about0.03 inches (from about 76.2 to about 762 microns). These thicknessranges provide resistance to wear, impact, FOD, etc. and the option tofinish more aggressively to meet dimensional tolerances, surface finishrequirements, etc. The metallic layer(s) 312 may be plated in multiplesteps by masking certain areas of the electrical control unit housing toyield different thicknesses (or no plating) in areas of interest forperformance or decorative purposes. Such a customized plating thicknessprofile can also be achieved by tailored racking (including shields,thieves, conformal anodes, etc.). Tailored racking permits foroptimization of properties for the electrical control unit housing withrespect to structural support, surface characteristics, etc. withoutadding undue weight to the housing. Further, the electrical control unithousing may be fabricated in multiple segments that are joined byconventional process (e.g., ultrasonic, laser, friction andfriction-stir welding processes; traditional welding processes;adhesives; mitered joints with or without adhesives) before plating.Furthermore, the electrical control unit housing may be produced in aplurality of segments that are plated separately and subsequently bondedby transient liquid phase (TLP) bonding.

The metallic layer(s) 312 may include of one or more metals including,but not limited: to nickel; cobalt; copper; iron; gold; silver;palladium; rhodium; chromium; zinc; tin; cadmium; and alloys with any ofthe foregoing elements comprising at least 50 wt. % of the alloy; andcombinations thereof. Plating may be performed in multiple steps bymasking certain areas of the molded article to yield differentthicknesses or no plating in certain areas. A customized platingthickness profile can also be achieved by tailored racking (includingshields, thieves, conformal anodes, etc.).

One or more polymeric coatings 314 may also be applied to the metalliclayer(s) 312 to produce a lightweight, stiff, and strong polymerappearing (non-conductive) housing. The polymeric coating(s) 314 may beapplied by conventional processes, such as spray coating or dip coating.

A lightweight, plated polymer housing for FADECs and other electricalelectronic control units provide a precisely engineered structure. Thedisclosed housings may be cheaper to manufacture and/or lighter thanprior-art housings due to the disclosed plated polymer technology.Further, the metal appearance of the housing may increase the resalevalue of the unit. Polymer outer surfaces are also possible, ifrequired.

Sound Attenuation Structures Made with Plated Polymers

There are two primary noise sources on a gas turbine engine—the fan andthe turbine(s). To help attenuate fan noise, which cannot be controlledat the source, gas turbine engine makers use sound damping features inthe walls of the fan duct. These features include honeycomb structures,which are both costly and difficult to manufacture.

An alternative sound-damping scheme is disclosed in the form ofsound/vibration damping structures made from plated polymers. Turning toFIG. 29, an exemplary sound/vibration damper 380 may include a hollowedpolymeric substrate 381 and one or more metallic layers 382. Thesubstrate 381 may be injection-molded, compression-molded, blow-molded,additively manufactured or a composite layup structure. The polymericsubstrate 381 may be formed from one or more polymers selected from thegroup consisting of: polyetherimide (PEI); polyimide; polyether etherketone (PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof. Thepolymeric substrate 381 may be fabricated around a suitable core toserve as an in situ mandrel and to provide the correct specific gravityand handling characteristics for the sound/vibration damper 380.

The metallic layer 382 may include one or more layers. Plating may beperformed in multiple steps by masking certain areas of the substrate381 to yield different thicknesses (or no plating) in areas of interestfor performance or for later introduction of discontinuous vibrationdamping materials for noise attenuating purposes. This customizedplating thickness profile can also be achieved by tailored racking(including shields, thieves, conformal anodes, etc.). Tailored rackingallows for optimization of properties for the vibration/noise dampenerwith respect to structural support, surface characteristics, etc.without adding undue weight to the sound/vibration damper 380. Themetallic layer(s) 382 may be then applied to the polymeric substrate 381by methods such as, but not limited to, electroless plating,electroplating or electroforming. The metallic layer 381 may be formedfrom one or more metals including, but not limited to: nickel; cobalt;copper; iron; gold; silver; palladium; rhodium; chromium; zinc; tin;cadmium; and alloys with any of the foregoing elements comprising atleast 50 wt. % of the alloy; and combinations thereof. Plating may beperformed in multiple steps by masking certain areas of the moldedarticle to yield different thicknesses or no plating in certain areas. Acustomized plating thickness profile can also be achieved by tailoredracking (including shields, thieves, conformal anodes, etc.).

The sound vibration damper 380 can be fabricated in multiple segmentsthat are joined by any conventional process (e.g., ultrasonic, laser,friction and friction-stir welding processes; traditional weldingprocesses; adhesives; mitered joints with or without adhesives) beforeplating. Furthermore, the vibration damper/attenuator 380 can beproduced and plated separately and subsequently bonded by transientliquid phase (TLP) bonding.

One or more polymeric coatings 384 may also be applied to the metalliclayer(s) 382 to produce a lightweight, stiff and strong polymerappearing (non-conductive) sound/vibration damper 380 or to enhanceperformance of the sound/vibration damper 380. The polymeric coating(s)384 may be applied by conventional processes, such as spray coating ordip coating. In addition, as shown in FIG. 29, the hollow portions 383of the plated polymer vibration damper/attenuator 380 may be filled withdiscontinuous vibration damping materials such as spheres 386 ormicro-balloons 387 to enhance the acoustic damping performancesound/vibration damper 380. Alternatively, as shown in FIG. 30, thepolymeric substrate 381 may be removed after the metallic layer(s) 382are plated onto the polymeric substrate 381 (FIG. 29) and refilled withhigher temperature materials such as ceramic beads or microspheres 388to permit use of the sound/vibration damper 380 a in high-temperatureenvironments.

Thus, disclosed vibration damper/attenuators may not only reducetransmitted noise from the fan blades, but could also be used in ahigh-temperature exhaust system. The durability of the disclosedvibration damper/attenuator may also offer improved durability overtraditional honeycomb materials.

Drive and Transmission Shafts Made from Plated Polymeric Substrates

Drive shafts, transmission shaft and rotors are used to transmit powerand torque from a drive component to a driven component. Typically, suchshafts are made from metal materials or alloys due to high strength andstiffness requirements. However, metal shafts are heavy and costly.Thus, high strength, high torque shafts that are lighter than metalshafts but perform as well as metal shafts would be of value to payloaddriven platforms.

Turning to FIG. 31, an exemplary hybrid metal-composite drive or torquetransmission shaft 390 may include a polymeric substrate 391 and one ormore metallic layers 392. The exemplary substrate 391 isinjection-molded, compression-molded, blow-molded, additivelymanufactured or a composite layup structure formed from at least onepolymer selected from the group consisting of: may include, but are notlimited to: polyetherimide (PEI); polyimide; polyether ether ketone(PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof. Thepolymeric substrate 391 may be fabricated around a suitable core toserve as an in situ mandrel and to provide the correct specific gravityand handling characteristics for the hybrid metal-composite drive ortorque transmission shaft 390. The metallic layer(s) 392 may be appliedby electroless plating, electroplating, or electroforming to a thicknessranging from about 0.01 to about 0.5 inches (from about 0.254 to about12.7 mm) An average plating thickness may range from about 0.025 toabout 0.25 inches (from about 0.635 to about 6.35 mm) These thicknessranges provide resistance to wear, impact, FOD, etc. and the option tofinish more aggressively to meet dimensional tolerances, surface finishrequirements, etc.

The metallic layer 392 may be plated in multiple steps by maskingcertain areas of the formed polymeric substrate 391 to vary thethickness of the metallic layer 392 for performance or handlingpurposes. Such a customized plating thickness profile may also beachieved by tailored racking (including shields, thieves, conformalanodes, etc.). Tailored racking allows for optimization of properties ofthe shaft 390 with respect to structural support, surfacecharacteristics, etc. without adding undue weight to the shaft 390. Theshaft 390 may be fabricated in multiple segments that are joined by aconventional process (e.g., ultrasonic, laser, friction andfriction-stir welding processes; traditional welding processes;adhesives; mitered joints with or without adhesive) before plating.Furthermore, the shaft 390 may be produced in multiple segments that maybe plated separately and subsequently bonded together by transientliquid phase (TLP) bonding.

Thus, a hybrid metal-composite drive or torque transmission shaft can beproduced which is lighter in weight than traditional all metal shafts.The hybrid construction using a plated polymers can produce a higherstiffness and lighter weight shaft, at similar or lower cost.

Plated Polymer Valve Housings or Enclosures

Valves used for aircraft engines typically employ metal housings orenclosures. A valve typically includes one or more inlets and one ormore outlets to control flow. Metal valve housings are heavy andtherefore add unwanted weight to the aircraft. Thus, durable, butlighter alternatives are desired.

Turning to FIG. 21, an exemplary valve housing may include a polymericsubstrate 311 and a metallic layer 312. The exemplary substrate 311 maybe an injection-molded, compression-molded, blow-molded, additivelymanufactured or a composite-layup structure formed from at least one ofthe following polymers: polyetherimide (PEI); polyimide; polyether etherketone (PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof

The metallic layer 312 may include one or more layers. The metalliclayer(s) 312 may be applied by electroless plating, electroplating, orelectroforming to a thickness ranging from about 0.01 to about 0.09inches (from about 0.254 to about 2.29 mm, locally. An average platingthickness may range from about 0.015 to about 0.08 inches (from about0.381 to about 2.03 mm) These thickness ranges provide resistance toerosion, impact, FOD, etc. and the option to finish more aggressively tomeet tight tolerances, surface finish requirements, etc. The metalliclayer(s) 312 may include any one or more of the following: nickel;cobalt; copper; iron; gold; silver; palladium; rhodium; chromium; zinc;tin; cadmium; and alloys with any of the foregoing elements comprisingat least 50 wt. % of the alloy; and combinations thereof.

The metallic layer(s) 312 may be plated in multiple steps by maskingcertain areas of the formed polymeric substrate to yield differentthicknesses (or no plating) in areas of interest. Such a customizedplating thickness profile may also be achieved by tailored racking(including shields, thieves, conformal anodes, etc.). Tailored rackingprocess permits optimization of properties for the valve housing withrespect to fire resistance, structural support, surface characteristics,etc. without adding undue weight to the valve housing.

Some mounting features (e.g., flanges or bosses) may be bonded to thesubstrate 311 using a suitable adhesive after molding but before platingto simplify the mold tooling. More broadly, the valve housing may befabricated in multiple segments that are joined by a conventionalprocess (e.g., ultrasonic, laser, friction and friction-stir weldingprocesses; traditional welding processes; adhesives; mitered joints withor without adhesive) before plating. Furthermore, the valve housing maybe produced and plated separately and subsequently bonded by transientliquid phase (TLP) bonding. In addition, features such as bosses orinserts may be added (using an adhesive, riveting, etc.) to the partafter the plating process.

One or more polymeric coatings 314 may also be applied to the platedpolymer valve housing to produce a lightweight, stiff, and strongpolymer appearing (non-conductive) valve housing. The polymericcoating(s) 314 may be applied by conventional processes, such as spraycoating or dip coating.

Thus, plated polymer valve housings or enclosures offer cost and/orweight savings compared to traditional metal materials. The molding ofthe polymeric substrate and the plating of the molded polymericsubstrate are both high-throughput processes. Further, complex housinggeometries may be accommodated by producing multiple polymer segmentsand joining them together before plating of after plating using TLPbonding.

Plated Polymer Fan Case Ice Impact Panel

During operation of a gas turbine engine, ice may accumulate on the fanblades before it is shed from the fan blades in a radially outward andin the aft direction. Thus, as the ice is forced radially outward andaft of the fan blades, the ice impacts the inner flow path surface ofthe fan case. To insure that the impact of the ice does not result indamage to the inner flow path surface of the fan case, ice impact panelsare known and are installed on the fan case. Typically, an ice impactpanels is a Kevlar/epoxy composite laminate. Such composite laminate iceimpact panels work well at resisting damage from ice impact, but arerelatively expensive to manufacture. Thus, an effective but cheaperalternative is needed.

Referring to FIGS. 6 and 32, an improved ice impact panel 400 isdisclosed that is fabricated using plated thermoplastics to replace thecurrently employed laminate ice impact panels. The overall size andshape of the existing panel may be maintained, but a polyetherimide(PEI) or similar thermoplastic may be injection molded to create apolymeric substrate 401 in the shape of the ice impact panel 400. Othermaterials for the polymeric substrate 401 include, but are not limitedto: polyetherimide (PEI); polyimide; polyether ether ketone (PEEK);polyether ketone ketone (PEKK); polysulfone; polyamide; polyphenylenesulfide; polyester; polyimide; and combinations thereof. Suitablethermoset materials may include, but are not limited to: condensationpolyimides; addition polyimides; epoxy cured with aliphatic and/oraromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 401 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 401 may include aplurality of layers to form a composite layup structure.

The substrate 401 is then coated with at least one metallic layer 402,and preferably multiple metallic layers. The metallic layers may includenickel or sulfamate nickel to improve the strength and impact resistanceof the thermoplastic substrate 401 such that it can withstand the iceimpact. Other suitable metals include, but are not limited to: nickel;cobalt; copper; iron; gold; silver; palladium; rhodium; chromium; zinc;tin; cadmium; and alloys with any of the foregoing elements comprisingat least 50 wt. % of the alloy; and combinations thereof. Plating may beperformed in multiple steps by masking certain areas of the moldedarticle to yield different thicknesses or no plating in certain areas. Acustomized plating thickness profile can also be achieved by tailoredracking (including shields, thieves, conformal anodes, etc.).

Thus, plated polymer ice impact panels may be fabricated from a moldedpolymer substrate that may be plated to provide ice impact panels thatare cheaper to make but as effective as the currently employed compositelaminate ice impact panels.

Plated Polymer Tubes and Connectors

An oil or lubrication system of a gas turbine engine, or any similartype of engine, may provide pressurized and heated oil to one or morebearings, a gearbox, a gear train, etc. A lubrication system for anengine may include a plurality of tubes and connectors. Such tubes andconnectors are normally machined out of stainless steel because ofinternal pressure, temperature and anti-erosion requirements and toprevent oil leaks at preformed seals. The manufacturing costs of suchtubes and connectors can be high due to the high-precision machining andcorrosion resistant steel used to fabricate the tubes and connectors.Because of the use of stainless steel as the material of construction,such stainless steel tubes and connectors are heavy in comparison toparts fabricated from thermoplastic materials. As a result, stainlesssteel or metal tubes and connectors add weight to the engine, whichreduces the fuel efficiency of the engine. However, replacing thestainless steel or metal in such tubes and connectors with a lighter,different metal is problematic due to the operating conditions of manygas turbine engines, including those used to power aircraft. Forexample, many thermoplastic materials are not suitable for aircraftengine applications because, in the case of lubrication system tubes andconnectors, the material must be able to withstand continuous operatingtemperatures of 177° C. (350° F.) or higher while also enduring thermalcycles and internal pressure requirements.

To provide durable and lightweight tubes and connectors for use inengines that have relatively complex geometries and that operate inrelatively extreme environments, disclosed herein are tubes andconnectors made from molded or machined or additively manufacturedpolymeric materials that are plated. The disclosed tubes and connectorshave a comparably low weight and may offer reduced manufacturing costs.

To reduce the weight and cost of tubes and connectors for engines thatoperate in harsh environments, composite tubes, connectors, nozzles,etc. are disclosed like the exemplary tube/connector 410 shown in FIGS.33A and 33B. The exemplary tube/connector 410 is fabricated from aformed thermoplastic material and plating to provide the necessarystrength, thermal, and anti-erosion properties. The tube/connector 410is first molded or machined using conventional methods to form apolymeric substrate 411 of the desired shape. The polymeric substrate411 may include one or more thermoplastic materials selected from groupconsisting of: polyetherimide (PEI); polyimide; polyether ether ketone(PEEK); polyether ketone ketone (PEKK); polysulfone; polyamide;polyphenylene sulfide; polyester; polyimide; and combinations thereof.Suitable thermoset materials may include, but are not limited to:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 411 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 411 may include aplurality of layers to form a composite layup structure.

After the polymeric substrate 411 is formed as shown in FIG. 33A, it iscoated with an activation layer 414 (not shown in FIG. 33A, see FIG.33B) and then plated with one or more metallic layers, two of which areshown at 412, 413 in FIGS. 33A and 33B. The activation layer 414 (FIG.33B) typically includes copper. The plated metallic layers 412, 413 mayinclude conventional plating materials and may be applied to thepolymeric substrate 411 and activation layer 414 using conventionalprocesses such as electrolytic plating or electroless plating. Forexample, the activation layer may include copper, the metallic layers412, 413 may include nickel and may have thicknesses ranging from aboutone (1) to four (4) thousandths of an inch. One example for a structurewith an activation layer 414 and two metallic layers 412, 413 is toapply a copper activation layer 414, a first electroless nickel layer412, and a second electrolytic nickel layer 413. Such a multi-layerstructure may provide strength and ductility in the activation layer 414and metallic layer(s) 412 and high stiffness in the outer metallic layer413. An electroless-plated nickel layer 412 or 413 may ensure coveragefor high aspect ratio features, such as the hole 415 and the recess 416.Electroless plating may also provide a uniform thicknesses for themetallic layer(s) 412 or 413. The plating may be formed from one or moremetals including, but not limited: nickel; cobalt; copper; iron; gold;silver; palladium; rhodium; chromium; zinc; tin; cadmium; and alloyswith any of the foregoing elements comprising at least 50 wt. % of thealloy; and combinations thereof. Plating may be performed in multiplesteps by masking certain areas of the molded article to yield differentthicknesses or no plating in certain areas. A customized platingthickness profile can also be achieved by tailored racking (includingshields, thieves, conformal anodes, etc.).

The tube/connector 410 may be machined, as necessary, to the requireddimensions using conventional methods. For example, the polymericsubstrate 411 may be machined as necessary after molding and/or afterapplication of the metallic layer(s) 412, 413. Tight tolerancerequirements may be met with conventional machining processes. Inaddition, the thin metallic layer 412 provided in the above example maynot be necessary.

To ensure a thick, uniform layer of metal in the internal passage 417 ofthe tube/connector 410, a metal tube 418 (e.g., stainless steel or acomparable metal or alloy) may be inserted into the passage 417 toprovide additional support and resistance to erosion, etc. The metaltube 418 could be inserted before or after the plating process. Inaddition, the polymeric substrate 411 may be co-molded with the metaltube 418 in place.

The tube/connector 410 may also be a nozzle. In the case of nozzles withsmall holes, metal tubular inserts 418 could be used to line theinternal passage 417 to ensure coverage of small channels or passageswith metal.

Thus, plated polymer tubes, connectors, and nozzles are lighter inweight compared to their steel counterparts. The plating may providedimensional stability for parts under substantial internal pressures athigh temperatures. Certain complex geometries found in tubes, connectorsand nozzles might be easier to fabricate using a forming process ascompared to machining a part from stock material. Furthermore, formed ormachined polymeric substrates may be produced separately andsubsequently bonded together before plating to create a more complexplated part. Further, complex geometries may be accommodated byproducing multiple polymer segments and joining them together afterplating using TLP bonding. Further, plated polymer parts may be producedin high volumes with faster turnaround times than parts made bymachining.

Plated Polymer Gearbox Covers

Turning to FIG. 34, a gearbox cover 420 shown for installation in thegas turbine engine 110 of FIGS. 1-2. The gearbox cover 420 is essentialto the assembly, operation, and protection of critically toleranced,internal components disposed within the gearbox (not shown). The gearboxcover 420 may be designed to precisely align and control position ofhighly sensitive gears, bearings, seals, and other dynamic componentsthroughout a wide temperature spectrum. The gearbox cover 420 may alsoprovide static interfaces to align and structurally support aerospacecomponents such as hydraulic pumps, fuel pumps, oil pumps, andgenerators. The gearbox cover 420 may also provide potential mountinginterfaces with the engine case to help support the entire gearbox andit may protect internal components from environmental effects such asliquids, dust, and other debris to minimize corrosion and FOD. Finally,the gearbox cover 420 may contain oil in the gearbox and provide oilpaths and jets vital to the lubrication and cooling of engine componentsincluding gears, bearings, and seals.

The exemplary gearbox cover 420 may include a polymeric substrate 311and one or more metallic layers 312 as shown in FIG. 21. The gearboxcover 420 may be used to replace a machined aluminum or magnesiumbaseline gearbox cover. The geometry of the cover 420 may includevarying thicknesses with build-ups for attachments and holes for fluidflow and/or detailed installations. The metallic layer 312 be plated inmultiple steps by masking certain areas of the substrate 311 to yielddifferent thicknesses in areas of interest. Alternatively, tailoredracking used for plating the cover 420 can be developed to cause anuneven distribution of the plating that forms the metallic layer(s) 312.For example, a thicker metallic layer 312 can be provided on the insideof the cover for structural integrity during an external fire. Inaddition, a thicker metallic layer 312 allows for more aggressivemachining, finishing, etc. to achieve the desired surface roughness,tight tolerances (e.g., bore locations, flat surfaces), etc. in certainlocations of the part. The multi-step plating process allows foroptimization of cover properties, with respect to fire, structuralsupport, surface characteristics, etc. without adding undue weight tothe cover 420.

The exemplary substrate 311 may be injection-molded or compressionmolded formed at least one polymer selected from the group consistingof: polyetherimide (PEI); polyimide; polyether ether ketone (PEEK);polyether ketone ketone (PEKK); polysulfone; polyamide; polyphenylenesulfide; polyester; polyimide; and combinations thereof. Suitablethermoset materials may include, but are not limited to: condensationpolyimides; addition polyimides; epoxy cured with aliphatic and/oraromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 311 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 311 may include aplurality of layers to form a composite layup structure.

Some mounting features (e.g., flanges or bosses) may be bonded to thesubstrate 311 using a suitable adhesive after molding but before platingto simplify the mold tooling. Further, the cover 420 may be fabricatedby molding the substrate 311 in separate, multiple segments that aresubsequently joined by a conventional process (e.g., ultrasonic, laser,friction and friction-stir welding processes; traditional weldingprocesses; adhesives; mitered joints with or without adhesive) beforeplating. Further, complex geometries may be accommodated by producingmultiple polymer segments and joining them together after plating usingTLP bonding.

An injection-molded polymeric substrate 311 may have thickness rangingfrom about 0.05 to about 0.2 inches (from about 1.27 to about 5.08 mm)On the other hand, a compression-molded polymeric substrate 311 may havea thickness ranging from about 0.05 to about 2 inches (from about 1.27to about to about 50.8 mm) In addition, reinforcing fibers (e.g., glassand/or carbon fibers) may be locally added, as required, to meetstructural requirements.

From about 10 to about 60 wt % of the gearbox cover 420 may beattributed to the metallic layer(s) 312. Portions of the metalliclayer(s) 312 may be purposefully weakened (or the polymeric substratecan be masked before plating) to provide paths for outgassing andexpansion of the polymeric substrate during a fire. The weakenedportions should not reside near areas of the gearbox cover 420 that maybe significantly stressed or that experience stress concentrations. Suchweakened portions may be used to provide appropriate redirection ofthermally-induced stresses and strains away from critical load paths.The metallic layer(s) 312 may be applied by electroplating orelectroforming to a thickness ranging from about 0.01 to about 0.1inches (from about 0.254 to about 2.54 mm) The metallic layer(s) 312 maybe formed from one or more metals including, but not limited: nickel;cobalt; copper; iron; gold; silver; palladium; rhodium; chromium; zinc;tin; cadmium; and alloys with any of the foregoing elements comprisingat least 50 wt. % of the alloy; and combinations thereof. Plating may beperformed in multiple steps by masking certain areas of the moldedarticle to yield different thicknesses or no plating in certain areas. Acustomized plating thickness profile can also be achieved by tailoredracking (including shields, thieves, conformal anodes, etc.).

Thus, gearboxes made from plated polymers may provide cost or weightsavings. Further, fabricating a gearbox from a plated polymer may yieldlower lead times, which is a significant advantage over the normallylong lead-time required for gearbox covers. As a result, using platedpolymers for gearboxes provides increased flexibility in the detaileddesign phase of engine development and shorter baseline schedules forcover/housing developments, which both have a significant impact onprogram costs, even though they do not necessarily make the gearboxitself less expensive than a metal counterpart.

One-Piece, Injection-Molded Spinner Cone for Fan Section of Gas TurbineEngine

Referring to FIG. 35, a prior art spinner 430 and a nose cap 431 areshown that form the flow path forward of the fan blades 432 (see FIGS.1-2 and 6). The spinner 430 and the nacelle inlet 193 (FIGS. 1 and 6)influence the blade inlet air profile. The spinner 430 must, byregulation, resist impact from hail and bird strikes. The prior artspinner 430 may be fabricated from a pre-impregnated KEVLAR® compositethat may be resin transfer molded, compression molded, or bladdermolded. The spinner 430 may be autoclaved or oven cured. The spinner 430is typically a separate part from the nose cap 431, which may also befabricated from a resin-impregnated KEVLAR® composite that iscompression molded. With these manufacturing methods, the mostcost-effective way to add stiffness to the spinner 430 or nose cap 431is to increase the thicknesses, thus adding weight in addition tomaterial and processing costs.

Improved light weight and stiff forward cones 440, 450, 470 are shown inFIGS. 36, 37, 38 respectively. The unitary forward cones 440, 450, 470may replace the combination of the separate spinner 430 and nose cap 431shown in FIG. 35. The forward cones 440, 450, 470 may be injectionmolded and, in the case of the cones 440, 450, may be provided withreinforcements in the form of ribs 441, 442 in the circumferentialand/or axial directions respectively. The ribs 441, 442 add stiffness tothe forward cone without adding overall thickness or significant weightto the forward cones 440, 450. The number of circumferential ribs 441may range from about two (2) to about 20, inclusive. The number of axialribs 442 (spline-shaped, running forward to aft) may range from aboutthree (3) to about 32, inclusive. As shown in FIG. 37, optional shearties or ribs 443 connecting intersections of the circumferential andaxial ribs 441, 442 may also be used to add additional stiffness to theoverall structure. The area enclosed by the intersecting circumferentialand axial ribs 441, 442 essentially form rectangles at the aft ends 444,445 of the forward cones 440, 450 respectively and transition totrapezoids (and finally triangles, if the ribs are carried all the wayto the forward ends 446, 447 of the cones 440, 450 respectively. Theafore-mentioned shear ties or ribs 443 shown in FIG. 37 may beincorporated between all such enclosed areas, in alternating areas (likea chess board), in alternating rows or columns, etc., as required todeliver the necessary stiffness and other relevant properties.

Due to the injection molding process, the ribs 441, 442, 443 may requirea draft angle for removal from the mold tool (not shown), and athickness and height of the ribs 441, 442, 443 may primarily be afunction of the cone thickness due to shrinkage concerns. Regardless,the quantity and spacing of the ribs 441, 442 and the optional shearties or ribs 443 and the overall thickness of forward cones 440, 450,470 (with and without the ribs 441, 442 and shear ties 443) may beoptimized. The ribs 441, 442, 443 do not have to be evenly spaced.

Referring back to FIG. 21 and to FIG. 38, molded polymeric substrates311 form cores for the forward cones 440, 450, 470 that may be platedusing a thin activation layer of copper to activate the polymericsubstrate 311. The metallic layer(s) 312 may be applied by electrolessplating, electroplating, or electroforming to a thickness ranging fromabout 0.004 to about 0.05 inches (from about 101.6 microns to about 1.27mm) The metallic layer(s) 312 may be formed from one or more metalsincluding, but not limited: nickel; cobalt; copper; iron; gold; silver;palladium; rhodium; chromium; zinc; tin; cadmium; and alloys with any ofthe foregoing elements comprising at least 50 wt. % of the alloy; andcombinations thereof. Plating may be performed in multiple steps bymasking certain areas of the molded article to yield differentthicknesses or no plating in certain areas. A customized platingthickness profile can also be achieved by tailored racking (includingshields, thieves, conformal anodes, etc.).

The plating of the polymeric substrate 311 produces lightweight forwardcones 440, 450, 470 with high specific strength and resistance tocertain environmental concerns, e.g., erosion. Variations in the desiredwall thickness or thickness of the polymeric substrate 311 may be easilyaccommodated in the molding process. The exemplary substrate 311 may beinjection-molded or compression-molded and formed from one or morepolymers selected from the group consisting of: condensation polyimides;addition polyimides; epoxy cured with aliphatic and/or aromatic aminesand/or anhydrides; cyanate esters; phenolics; polyesters;polybenzoxazine; polyurethanes; polyacrylates; polymethacrylates;silicones (thermoset); and combinations thereof. Optionally, thepolymeric material of the polymeric substrate 311 may be structurallyreinforced with materials that may include carbon, metal, or glass. Thefiber-reinforced polymeric substrate 311 may include a plurality oflayers to form a composite layup structure.

The forward cones 440, 450, 470 necessarily include mounting features(of which only a flange 471 is shown in FIG. 38). Some of these features(e.g., flanges) may be bonded to the polymeric substrate 311 (FIG. 21)using a suitable adhesive after molding but before plating to simplifythe mold tooling. A similar approach can be taken with additionalfeatures, such as the ribs 441, 442 and 443 (i.e., the can be integralin the mold tooling or bonded on after molding to simplify that process.

Thus, one-piece, injection-molded and plated forward cone (i.e., acombination nose cap and spinner) may be manufactured for a lower costthan prior art nose caps and spinners. The disclosed forward cone may beunitary, thereby replacing two parts (a nose cap and a spinner) with asingle unitary forward nose cone. Disclosed one-piece, injection-moldedcores that are plated with a metallic layer can be manufactured for amuch lower cost than KEVLAR composites of the prior art. The disclosedforward cones are lighter and new designs may be fabricated with shorterlead times. The plated metallic layer(s) provides resistance to erosionwhile typical prior art spinners require an additional coating forerosion resistance. The disclosed nose cones may include reinforcingelements in the form of an internal ribbed structure designed to carryand distribute static and impact loads throughout the forward cone moreefficiently than a constant thickness structure. Therefore, the wallthickness of the forward cone may be reduced to save weight.

Plated Polymer Attachment Rings

In a gas turbine engine 110 (FIGS. 1-2 and 6), a spinner attachment ringmay be used to attach a spinner or nose cone to a non-rotating hub, arotating hub, or a fan rotor (not shown). In general, spinner attachmentrings may also transmit loads and may serve secondary functions such asretaining locks, etc. Spinner attachment rings are typically made of ametal, such as titanium, iron, or aluminum. These types of rings tend tobe heavy and expensive.

An exemplary spinner attachment ring 460 is shown in FIG. 38. Thespinner attachment ring 460 may include a polymeric substrate 311 and atleast one metallic layer 312 as shown in FIG. 21. The exemplarysubstrate 311 may be injection molded or compression molded and mayinclude any one or more polymers selected from the group consisting of:condensation polyimides; addition polyimides; epoxy cured with aliphaticand/or aromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 311 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 311 may include aplurality of layers to form a composite layup structure.

The metallic layer 312 may include one or more layers. The metalliclayer(s) may be applied by electroless plating, electroplating, orelectroforming to a thickness ranging from about 0.001 to about 1 inch(from about 25.4 microns to about 2.54 cm), locally. An average platingthickness may range from about 0.01 to about 0.075 inches (from about254 microns to about 1.91 mm) These thickness ranges provide resistanceto erosion, impact, etc. and the option to finish more aggressively tomeet tight tolerances, surface finish requirements, etc. The metalliclayer 312 may be formed from one or more metals including, but notlimited: nickel; cobalt; copper; iron; gold; silver; palladium; rhodium;chromium; zinc; tin; cadmium; and alloys with any of the foregoingelements comprising at least 50 wt. % of the alloy; and combinationsthereof

The metallic layer(s) 312 may be applied in multiple steps by maskingcertain areas of the attachment ring to yield different thicknesses inareas of interest, such as platforms or flanges. Such a customizedplating thickness profile may also be achieved by tailored racking(includes shields, thieves, etc.). In addition, a thicker metalliclayer(s) 312 allows for more aggressive machining, finishing, etc. toachieve the desired surface roughness, tolerances, etc. Such amulti-step process allows for optimization of attachment ringproperties, with respect to fire, structural support, surfacecharacteristics, etc. without adding undue weight to the attachment ring460.

Further, the attachment ring 460 may be fabricated in multiple segmentsthat are joined by any a conventional process (e.g., ultrasonic, laser,friction and friction-stir welding processes; traditional weldingprocesses; adhesives; mitered joints with or without adhesive) beforeplating. Because the metallic layer 312 is thick enough to providesignificant structural strength and rigidity, the method of joiningsegments will likely not be a strength limiting factor.

Thus, plated polymer attachment rings are disclosed that haveapplications beyond attaching a spinner or forward cone to a hub. Thedisclosed attachment rings are relatively inexpensive to manufacture dueto the high-throughput molding and plating processes used to make therings.

Plated Polymer Textured Surface for Water and Ice Management

Some component surfaces of gas turbine engines require protectionagainst erosion and de-icing capability. Current materials that arerelatively erosion resistant include metals, ceramics, and somepolymers. It is desirable to simultaneously provide an erosion resistantmaterial that also repels or selectively directs water and/or preventsice buildup on the component surfaces.

Turning to FIG. 39, disclosed herein is a technique to impart a designedtexture onto or into a surface 480 of an erosion resistant material usedto fabricate a plated polymer spinner or forward cone. The texturedsurface 480 is designed to control the contact angle of the wettingfluid 481 (water) to direct the fluid 481 off the textured surface 480and/or to prevent ice formation on the textured surface 480. Additionaltreatments can be performed to further enhance the functionality of thetextured surface 480.

At least one metallic layer 483 is plated on top of a textured polymericsubstrate 482, which can render the textured surface 480 with even moreresistance to erosion and super-hydrophobicity to prevent waterattachment, and thus, to minimize ice buildup/adhesion. The substrate482 may include, but is not limited to: polyetherimide (PEI); polyimide;polyether ether ketone (PEEK); polyether ketone ketone (PEKK);polysulfone; polyamide; polyphenylene sulfide; polyester; polyimide; andcombinations thereof. Suitable thermoset materials may include, but arenot limited to: condensation polyimides; addition polyimides; epoxycured with aliphatic and/or aromatic amines and/or anhydrides; cyanateesters; phenolics; polyesters; polybenzoxazine; polyurethanes;polyacrylates; polymethacrylates; silicones (thermoset); andcombinations thereof. Optionally, the polymeric material of thepolymeric substrate 482 may be structurally reinforced with materialsthat may include carbon, metal, or glass. The fiber-reinforced polymericsubstrate 482 may include a plurality of layers to form a compositelayup structure. The metallic layer(s) 483 may be formed from one ormore metals including, but not limited: nickel; cobalt; copper; iron;gold; silver; palladium; rhodium; chromium; zinc; tin; cadmium; andalloys with any of the foregoing elements comprising at least 50 wt. %of the alloy; and combinations thereof. Plating may be performed inmultiple steps by masking certain areas of the molded article to yielddifferent thicknesses or no plating in certain areas. A customizedplating thickness profile can also be achieved by tailored racking(including shields, thieves, conformal anodes, etc.).

The metallic layer(s) 483 provide erosion and fatigue resistance. Themetallic layer 483 may include one or more layers, preferably with anon-hydrophilic top-most layer. The metallic layer(s) 483 may be appliedby electroless plating, electroplating, or electroforming to a thicknessof about 10% of the texture dimension h.

Thus, as opposed to prior art hardening or coating techniques includingnitriding and aluminizing to avoid erosion, texture plated polymersurfaces are disclosed, for example, a textured plated polymer forwardcones, nose cones or spinners. The textured plated polymer design savesboth weight and costs and can generate a textured metallic layer of auniform thickness.

Impact-Resistant Plated Polymer Structures

Many components of a gas turbine engine must be resistant to impactevents from both hard objects (rocks, debris, ice, etc.) and softobjects (bird strikes, etc.). Components of other engines, such astruck, automotive, marine, etc., also must be resistant to such impactevents. Components made from traditional materials such metals,polymers, composites, ceramics, etc. often must be made heavier or withmore complex geometries to meet impact-resistant requirements. Heaviercomponents and/or components with more complex geometries increase costand manufacturing lead time as well as substantial design andmanufacturing efforts.

Turning to FIG. 40, disclosed herein are impact-resistant plated polymerstructures 500, which may include a polymeric substrate 501 covered byat least one metallic layer 502. An exemplary substrate 501 may beinjection-molded, compression-molded, blow-molded, additivelymanufactured or a composite-layup structure. The polymeric substrate 501may be formed of at least polymer selected from the group consisting of:polyetherimide (PEI); polyimide; polyether ether ketone (PEEK);polyether ketone ketone (PEKK); polysulfone; polyamide; polyphenylenesulfide; polyester; polyimide; and combinations thereof. Suitablethermoset materials may include, but are not limited to: condensationpolyimides; addition polyimides; epoxy cured with aliphatic and/oraromatic amines and/or anhydrides; cyanate esters; phenolics;polyesters; polybenzoxazine; polyurethanes; polyacrylates;polymethacrylates; silicones (thermoset); and combinations thereof.Optionally, the polymeric material of the polymeric substrate 501 may bestructurally reinforced with materials that may include carbon, metal,or glass. The fiber-reinforced polymeric substrate 501 may include aplurality of layers to form a composite layup structure.

The metallic layer(s) 502 may include one or more layers. The metalliclayer(s) 502 may be applied by electroless plating, electroplating, orelectroforming to a thickness ranging from about 0.001 to about 0.5inches (from about 25.4 microns to about 12.7 mm), locally. An averageplating thickness may range from about 0.004 to about 0.3 inches (fromabout 101.6 microns to about 7.62 mm) These thickness ranges providesresistance to erosion, impact, FOD, etc. and the option to finish moreaggressively to meet tight tolerances, surface finish requirements, etc.The plating of the metallic layer(s) 502 may be carried out in multiplesteps by masking certain areas of the polymeric substrate 501 to yielddifferent plating thicknesses (or no plating) in areas of interest. Sucha customized plating thickness profile may also be achieved by tailoredracking (including shields, thieves, conformal anodes, etc.). Tailoredracking allows for an optimization of properties for theimpact-resistant plated polymer structure 500 with respect to fireresistance, structural support, surface characteristics, etc. withoutadding undue weight to the structure 500. The metal layer(s) 502 may beformed from one or more metals including, but not limited: nickel;cobalt; copper; iron; gold; silver; palladium; rhodium; chromium; zinc;tin; cadmium; and alloys with any of the foregoing elements comprisingat least 50 wt. % of the alloy; and combinations thereof.

The impact-resistant plated polymer structure 500 may be fabricated inmultiple segments that may be are joined by a conventional process(e.g., ultrasonic, laser, friction or friction-stir welding processes;traditional welding processes; adhesives; mitered joints with or withoutadhesive) before plating. Such segments of a final structure 500 may beproduced and plated separately, and subsequently bonded together bytransient liquid phase (TLP) bonding. Features such as inserts ordetails may be added (using an adhesive, riveting, etc.) to thestructure 500 after the plating process. One or more polymeric coatings503 may also be applied to impact-resistant plated polymer structure 500to yield a lightweight, stiff and strong polymer appearing(non-conductive) component. The polymeric coating(s) 503 may be appliedby a conventional process, such as spray coating or dip coating, and maybe applied to localized regions only, if desired.

Turning to FIGS. 40-43, FIG. 40 illustrates molding parameters for apolymeric substrate 501 having reinforcing ribs 504. The moldingparameters for the ribs 504 illustrated in FIG. 40 include: (1) thethickness h₁ of polymeric substrate 501 (the sheet area between ribs504); (2) the height h₂ of the ribs 504; (3) the base width w₁ of theribs 504; (4) the tip width w₂ of the ribs 504; (5) the draft angle φ ofthe ribs 504; (6) the rib fillet radius r; and (7) the plating thicknesst. In general, the rib parameters illustrated in FIG. 40 are relatedaccording to the following equations:0.010×h ₁ ≤h ₂≤3.00×h ₁  Eq. A0.125×h ₁ ≤w ₁≤0.75×h ₁  Eq. B0.05 inch (1.27 mm)≤w ₂≤0.75×h ₁  Eq. C0°≤φ≤80°  Eq. D0.025 inch (635 microns)≤r  Eq. E0.001 inch (25.4 microns)≤t≤0.5 inch (12.7 mm)  Eq. F

Turning to FIG. 41, various rib patterns 510, 520, 530, 540 aredisclosed for arranging continuous ribs 504 on surface 505 of thepolymeric substrate 501 (FIG. 40). The rib patterns 510, 520, 530, 540provide the plated polymer structure 500 with isotropic properties whenthey are utilized in a repeating fashion. The efficiency of the finalstructure 500 will vary and depend upon the specific shape or ribpattern 510, 520, 530, 540 chosen. The ribs 504 of the patterns 510,520, 530, 540 may be flanged at the upper tips 506, which provide theribs 504 with an I-beam-like configuration to add additional structuralintegrity. Combinations of rib patterns 510, 520, 530, 540 may also beused, for example one combination pattern may involve six hexagonssurrounding a seventh hexagon that is filled with six triangles. Thepossible variations are too numerous to list individually here, as willbe apparent to those skilled in the art.

FIG. 42 is another disclosed rib pattern 550 that is an irregular grid.Regular grids may be used as well. FIG. 43 illustrates two unit-cellimpact-resistant patterns 560, 570 that may be applied uniformly or onlyin local areas where more impact resistance is required. The pattern 560includes triangular-shaped protrusions 561 that extend upward from thesurface 562 of the molded polymeric substrate 563. In contrast, thepattern 570 includes through-holes or recesses 571 that extend into orthrough the surface 572 of the molded polymeric substrate 573. Thepattern 560 includes triangular-shaped protrusions while the pattern 570includes hexagonal-shaped holes or recesses. Obviously, other shapes andcombinations of shapes may be used as will be apparent to those skilledin the art. The patterns 510, 520, 530, 540, 550 560, 570 illustrated inFIGS. 41-43 are mere examples that can be extended upon. Furthermore,the combinations of the rib patterns 510, 520, 530, 540, 550, 560, 570may be used, as desired, to achieve customized impact-resistanceproperties and redistribution of accompanying loads.

Plated Polymer Fan Blade and Method of Making

To date, fan blades used in gas turbine engines are generally fabricatedusing titanium, titanium alloys and/or laminated composite materials.The manufacture of fan blades with these materials tends to be expensiveand time consuming Additionally, many of these fan blades tend to berelatively heavy in order to possess the necessary ductility to survivebird strike events. As the mass of the fan blade increases, thelikelihood of case penetration in the event of blade breakage alsoincreases. Heavier fan blades also carry a heavier load, increasing therequirements of downstream engine components.

Turning to FIG. 44, an example of a dual-spool turbofan engine isdepicted. Turbofan engine 10 includes several sections: fan section 12,first low-pressure compressor section 14, second high-pressurecompressor section 16, combustor section 18, first high-pressure turbinesection 20, second low-pressure turbine section 22, bypass section 24,low-pressure shaft 26, and high-pressure shaft 28. A portion of theatmospheric air pulled in by rotation of fan section 12 is directedtoward first compressor section 14, while the remainder is directedtoward bypass section 24.

Air directed through first compressor section 14 is further compressedby second compressor section 16. Fuel is added and ignited in combustorsection 18. Blades in turbine sections 20 and 22 capture a portion ofthe energy from passing combustion products by turning turbine rotors.Both fan section 12 and first compressor section 14 are rotatably linkedvia low-pressure shaft 26 to first low-pressure power turbine section22. Second high-pressure compressor section 16 is rotatably connected tofirst high-pressure turbine section 22 via high-pressure shaft 28.Thrust is generated in engine 10 by the force of the air drawn in by fansection 12 and pushed through bypass section 24 (less any bleed air usedfor other aircraft functions), and by the force of exhaust gases exitingfrom second low-pressure turbine section 22.

In a turbofan engine, lighter components generally lead to moreefficient performance. If less energy is expended to move internalengine parts, more energy is available for useful work. At the sametime, the components themselves must be strong enough to withstandoperational forces, and types of failure typical for the operatingenvironment of the engine. Safety considerations and regulations basedon the frequency and/or severity of possible failure will often dictatethat the engine components also be able to withstand other atypical, yetforeseeable events. Because stronger and lighter components are oftenmore expensive, a balance must be struck between efficiency, safety, andcost.

Few locations in an aircraft are more representative of efforts tooptimize the balance between efficiency, safety, and cost than engine10. While lighter materials are preferable to improve efficiency, thehigh risk of severe consequences from engine damage will require thatengine 10 be made of components having additional margins of safety.Combining parts having both high strength and low density greatlyrestricts material choices and increases costs. Not infrequently,processing these strong and light materials such as titanium orcomposites is also complex and expensive.

Being designed to pull vast quantities of air through bypass section 24to generate thrust, blades in fan section 12 are the first line ofdefense for engine 10 and are highly susceptible to both small and largescale damage from objects pulled in with the surrounding air, includingbird impact damage.

Small scale blade damage causes performance deterioration and increasesthe number of potential crack initiation sites, while large scale damageincludes blade deformation and failure. Small impacts can also lead tolarge scale damage by serving as crack initiation sites. Larger impacts,such as ingestion of birds can cause one or more blades to deform orbreak in a single event. Regulations are in place to limit the frequencyand severity of single event failures because of the increased risk ofemergency landings and catastrophic failure.

Blades made entirely from high-strength materials, such as titanium ortitanium alloys like Ti-6A1-4V, have been proven to offer sufficienthardness to resist erosion and foreign object damage. But titaniumalloys are often expensive to purchase and manipulate into a finishedblade. And while titanium has a relatively low density compared to anumber of metals, the mass of titanium fan blades is a significantcontributor to overall engine mass.

Techniques have been developed to reduce costs and decrease mass bylimiting the amount of material needed to form blades. For example,hollow blades are common in higher output engines, minimizing the amountof titanium or strands of composite needed. In addition, designapproaches have been developed to minimize the mass impact of titaniumblades. Complex computer-aided modeling further provides efficient bladeshapes for a given application.

However, diminishing returns are seen with hollow blades in smallerengines. As the blades become smaller, the cavities also become smallerbecause the surfaces must have a certain thickness to maintain adequatestructural support. Hollow blades are not usually cost-effective insmaller engines with smaller components and less thrust because thesmaller cavity offers comparatively little mass savings. In smallengines, the costs saved by reducing mass are frequently offset by addedprocessing costs to form the smaller cavity.

Further, even in larger blades, current hollow metal blades arerelatively expensive to manufacture. Expensive and complex processessuch as diffusion bonding are often used to join two machined plates ortwo forged halves together into a large hollow blade. An expensiveprocess like diffusion bonding can partially or completely offset thedesired mass savings in some blades. Less expensive conventionalprocessing, such as welding, is not particularly useful for hollowtitanium blades because of the risk of stresses or brittleness caused byexcess heat around the joined areas or by the geometry of the weldjoint. Specialized and complex welding processes like laser or linearfriction welding are available to reduce these risks, but do notreliably provide sufficient bonding area or structural capability towithstand various impacts and vibratory stresses on the blade.

The following figures describe blades that can be adapted for use inexample dual-spool engine 10 shown in FIG. 44. In addition, the exampleblades described below can also be readily adapted for engines havingany number of spools, such as engines with single spool or three-spoolconstruction.

According to embodiments of the present invention, a fan blade containsa non-metallic core and a metallic layer covering at least a portion ofthe non-metallic core. FIG. 45 is a side view of fan blade 30. Fan blade30 includes airfoil 32, platform 33 and root 34. Airfoil 32 extends fromplatform 33 to blade tip 35. Platform 33 is an optional feature of fanblade 30. Platform 33 may be integral as shown, or may be omitted in thefan blade design and included in the engine as a separate part. Airfoil32 includes leading edge 36, trailing edge 38, pressure side surface 40and suction side surface 42. Fan blade 30 includes a metal layercovering a non-metallic core. FIG. 46 is a cross sectional view of thefan blade of FIG. 45 taken along the line 3-3 showing non-metallic core44 surrounded by metal layer 46.

Non-metallic core 44 is formed of a polymeric or composite material toreduce the overall mass of fan blade 30. In some embodiments,non-metallic core 44 is formed of a thermoplastic and/or thermosetmaterial. Suitable thermoplastic and thermoset materials include, butare not limited to, polyphenylene sulfides, polyamides,polyvinylchloride (PVC), polystyrene (PS), polyethylene (PE),polypropylene (PP), styrene-acrylonitrile (SAN), polycarbonate (PC),acrylonitrile styrene acrylate (ASA), acrylonitrile butadiene styrene(ABS), ethylene tetrafluoroethylene fluoropolymer (ETFE), high impactpolystyrene (HIPS), polyamide (PA), polybutylene terephthalate (PBT),polyetherimide (PEI), perchloroethylene (PCE), polyether sulfone (PES),polyethylene terephthalate (PET), polysulfone (PSU), polyurethane (PUR),polyvinylidene fluoride (PVDF), polyether ether ketone (PEEK),polyetherimide (PEI), thermoplastic polyimide, condensation polyimide,addition polyimide, polyether ketone ketone (PEKK), polysulfone,polyphenylsulfide, polyester, epoxy cured with aliphatic and/or aromaticamines and/or anhydrides, cyanate esters, phenolics, polyacrylates,polymethacrylates, silicones (thermoset), any of the foregoing withfiber reinforcement (e.g., carbon-fiber or glass-fiber) and combinationsthereof.

In some embodiments, non-metallic core 44 is formed by injectionmolding, resin transfer molding, vacuum-assisted resin transfer molding,composite layup (autoclave, compression, or liquid molding), compressionmolding, or additive manufacturing (liquid bed, powder bed, depositionprocesses). Alternatively, depending on its makeup, non-metallic core 44can also be formed by extrusion, thermoforming, weaving (2D or 3D),braiding, vacuum-forming, machining or laminating. Non-metallic core 44generally has a local thickness between about 1.27 mm (0.050 inches) andabout 50.8 mm (2 inches). Injection molded non-metallic cores 44generally have a thickness between about 1.27 mm (0.050 inches) andabout 5.08 mm (0.20 inches). Compression molded non-metallic cores 44generally have a thickness between about 1.27 mm (0.050 inches) andabout 5.08 cm (2 inches).

Non-metallic core 44 can be solid, as shown in FIG. 46, or non-metalliccore 44 can contain one or more cavities for receiving cooling air or tofurther reduce the overall mass of fan blade 30. In embodiments in whichnon-metallic core 44 contains cavities, cooling holes and slots canextend through non-metallic core 44 and metal layer 46.

At least a portion of non-metallic core 44 is covered by metal layer 46.In the embodiment shown in FIGS. 45 and 46, substantially all of fanblade 30 is covered by metal layer 46, including airfoil 32, platform 33and root 34. As shown in FIG. 46, metal layer 46 extends around all ofnon-metallic core 44, over leading edge 36, trailing edge 38, pressureside surface 40 and suction side surface 42.

Metal layer 46 can generally be formed from any metal having a meltingtemperature above about 150° C. (302° F.). Metal layer 46 can includesingle element metals and/or alloys. In some embodiments, metal layer 46includes nickel or nickel alloys.

In some embodiments, metal layer 46 has an average thickness betweenabout 0.254 mm (0.010 inches) and about 1.91 mm (0.075 inches), withlocal thicknesses between about 0.102 mm (0.004 inches) and about 5.1 mm(0.200 inches). Depending on the desired ductility and durability of fanblade 30, the thickness of metal layer 46 can be adjusted at variouslocations on fan blade 30. In some embodiments, metal layer 46 can bethicker along leading edge 36 or blade tip 35 than trailing edge 38 orplatform 33, respectively. For example, metal layer 46 can have athickness of about 2.54 mm (0.100 inches) at leading edge 36 and athickness of about 0.102 mm (0.004 inches) along pressure side surface40, suction side surface 42 and trailing edge 38.

Metal layer 46 can be applied to non-metallic core 44 by electroplating,electroless plating, electroforming, thermal spray coating, physicalvapor deposition, chemical vapor deposition and/or cold spraying.

Earlier attempts at metal plating polymers and composites demonstratedthat plating non-metallic cores with metal layers was prone tonodulation and pitting. Nodulation is the excessive build up of metallayer 46 along high current density locations of a part. Corners andedges of a plated part tend to receive larger amounts of plating whilerecesses receive less. Pitting refers to the formation of holes in metallayer 46 due to the presence of impurities in the plating bath. Thethicker the plating, the more pronounced the nodulation and pittingproblems become. These problems have discouraged others from attemptingto manufacture plated polymer fan blades that are capable of use withingas turbine engines.

Additionally, “racking” devices used to move parts in and out of platingbaths and hold the part within the baths can also provide plating weakpoints. The racking device contacts at least a portion of the part to beplated in order to hold the part. Typically, little plating is receivedin the region where the racking device contacts the part, resulting in aplating layer that is thinner near the racking point than elsewhere onthe part. Due to the thickness of the metal layer applied tonon-metallic core 44, different racking devices or racking points can beused for the metal plating of a particular part. For example, fan blade30 can be plated for a time with a racking point at an upstream portionof root 36 and a racking point at pressure side surface 40. Fan blade 30is then later plated with a racking point at a downstream portion ofroot 36 and a racking point at suction side surface 42. This evens outthe racking point locations to reduce or eliminate the presence of weakpoints in metal layer 46. “Shields”, “thieves” and masks can also beused during plating processes to modify the current density, andtherefore the amount of plating that is deposited on certain geometricfeatures. Shields force current to go around portions of the racking orthe component (i.e. fan blade) to be plated, slowing the rate of metaldeposition on regions under the shields. Thieves are typically metalparts positioned around or near the component to be plated that “steal”away plating by serving as a high current density location and reducingthe rate of metal deposition near the thief Masks cover a portion of thecomponent so that it does not receive any plating. These tools allowareas of fan blade 30 to be selectively plated and encourage ordiscourage the extent of plating in certain areas to modify thethickness of metal layer 46 in various regions.

In some embodiments, weak plating areas of metal layer 46 can bestrengthened using transient liquid phase (TLP) bonding. TLP bonding ofplated polymer components is discussed in greater detail in the U.S.patent application Serial No. 61/844,032, filed on Jul. 9, 2013. Thestrengthened bond provided by TLP bonding a metal-plated fan blade toanother metal-plated or metallic component can eliminate weak points inmetal layer 46 that formed as a result of a nearby racking point,nodulation or pitting while also allowing for flexibility in componentdesign. In some embodiments, metal layer 46 can also accommodate bondedmetal edges (leading edge, tip, trailing edge) using either adhesive orTLP bonding.

While FIGS. 45 and 46 illustrate fan blade 30 where substantially all ofthe blade is covered by metal layer 46, other embodiments can possessdiffering amounts of coverage. In some embodiments, metal layer 46covers only airfoil 32 or only airfoil 32 and platform 33. FIG. 47illustrates one embodiment of a fan blade in which the metal layercovers only the airfoil and the platform. Fan blade 30A shows metallayer 46A on airfoil 32A and platform 33A by way of stipling. In thisembodiment, root 34A does not include a metal layer. FIG. 48 illustratesone embodiment of a fan blade in which the metal layer covers only theairfoil. Fan blade 30B shows metal layer 46B on airfoil 32B by way ofstipling.

Embodiments of fan blade 30 having metal layer 46 covering non-metalliccore 44 are typically much lighter than fan blades constructed oftitanium or other metals. The lighter mass of fan blade 30 results in afan blade that is less likely to penetrate the fan case and raiseserious safety concerns in the event of blade breakage. Additionally,lighter fan blade 30 carries less load than comparable metal fan blades,allowing low-pressure power turbine section 22 downstream of fan section12 to be downsized, and therefore lighter, reducing overall engine mass.While fan blade 30 is lighter than conventional metal fan blades, therelatively thick metal layer 46 provides enough ductility and durabilityto survive bird strike events. In embodiments in which metal layer 46 isthickest along leading edge 36, blade durability is further improved.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A fan blade can include a root portion, a platform connected to the rootportion, and an airfoil portion extending from the platform to a tipregion. At least one of the root portion, the platform and the airfoilportion can include a non-metallic core having an outer surface and ametal layer covering a portion of the outer surface of the non-metalliccore.

The fan blade of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A further embodiment of the foregoing fan blade can further include thatthe non-metallic core has local thicknesses between about 1.27 mm (0.050inches) and about 50.8 mm (2.00 inches).

A further embodiment of any of the foregoing fan blades can furtherinclude that the metal layer has local thicknesses between about 0.102mm (0.004 inches) and about 5.1 mm (0.200 inches).

A further embodiment of any of the foregoing fan blades can furtherinclude that the metal layer has an average thickness between about0.254 mm (0.010 inches) and about 1.91 mm (0.075 inches).

A further embodiment of any of the foregoing fan blades can furtherinclude that the non-metallic core comprises a polymer selected from thegroup consisting of polyphenylene sulfides, polyamides,polyvinylchloride (PVC), polystyrene (PS), polyethylene (PE),polypropylene (PP), styrene-acrylonitrile (SAN), polycarbonate (PC),acrylonitrile styrene acrylate (ASA), acrylonitrile butadiene styrene(ABS), ethylene tetrafluoroethylene fluoropolymer (ETFE), high impactpolystyrene (HIPS), polyamide (PA), polybutylene terephthalate (PBT),polyetherimide (PEI), perchloroethylene (PCE), polyether sulfone (PES),polyethylene terephthalate (PET), polysulfone (PSU), polyurethane (PUR),polyvinylidene fluoride (PVDF), polyether ether ketone (PEEK),polyetherimide (PEI), thermoplastic polyimide, condensation polyimide,addition polyimide, polyether ketone ketone (PEKK), polysulfone,polyphenylsulfide, polyester, epoxy cured with aliphatic and/or aromaticamines and/or anhydrides, cyanate esters, phenolics, polyacrylates,polymethacrylates, silicones (thermoset), any of the foregoing withfiber reinforcement and combinations thereof.

A further embodiment of any of the foregoing fan blades can furtherinclude that the non-metallic core comprises composite materials.

A further embodiment of any of the foregoing fan blades can furtherinclude that the metal layer covers substantially all of thenon-metallic core.

A further embodiment of any of the foregoing fan blades can furtherinclude that the metal layer covers substantially all of the rootportion, the platform and the airfoil portion.

A further embodiment of any of the foregoing fan blades can furtherinclude that the metal layer substantially covers only the airfoil ofthe non-metallic core.

A further embodiment of any of the foregoing fan blades can furtherinclude that the metal layer substantially covers only the platform andthe airfoil of the non-metallic core.

A method for forming a fan blade with a metal covering can includeforming a non-metallic core and depositing a metal layer on a portion ofthe non-metallic core. The non-metallic core can include a platform, ablade root extending from the platform in a first direction for joiningwith a rotor hub, and an airfoil extending from the platform in a seconddirection generally opposite the first and having a tip generallyopposite the blade root.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A further embodiment of the foregoing method can further include thatthe non-metallic core comprises a polymer selected from the groupconsisting of polyphenylene sulfides, polyamides, polyvinylchloride(PVC), polystyrene (PS), polyethylene (PE), polypropylene (PP),styrene-acrylonitrile (SAN), polycarbonate (PC), acrylonitrile styreneacrylate (ASA), acrylonitrile butadiene styrene (ABS), ethylenetetrafluoroethylene fluoropolymer (ETFE), high impact polystyrene(HIPS), polyamide (PA), polybutylene terephthalate (PBT), polyetherimide(PEI), perchloroethylene (PCE), polyether sulfone (PES), polyethyleneterephthalate (PET), polysulfone (PSU), polyurethane (PUR),polyvinylidene fluoride (PVDF), polyether ether ketone (PEEK),polyetherimide (PEI), thermoplastic polyimide, condensation polyimide,addition polyimide, polyether ketone ketone (PEKK), polysulfone,polyphenylsulfide, polyester, epoxy cured with aliphatic and/or aromaticamines and/or anhydrides, cyanate esters, phenolics, polyacrylates,polymethacrylates, silicones (thermoset), any of the foregoing withfiber reinforcement and combinations thereof

A further embodiment of any of the foregoing methods can further includethat the non-metallic core comprises composite materials.

A further embodiment of any of the foregoing methods can further includethat the non-metallic core is formed by injection molding.

A further embodiment of any of the foregoing methods can further includethat the non-metallic core has local thicknesses between about 1.27 mm(0.050 inches) and about 5.08 mm (0.200 inches).

A further embodiment of any of the foregoing methods can further includethat the non-metallic core is formed by compression molding.

A further embodiment of any of the foregoing methods can further includethat the non-metallic core has local thicknesses between about 1.27 mm(0.050 inches) and about 50.8 mm (2.00 inches).

A further embodiment of any of the foregoing methods can further includethat the metal layer is deposited on the non-metallic core by a processselected from electroplating, electroless plating, electroforming,thermal spray coating, physical vapor deposition, chemical vapordeposition, cold spraying and combinations thereof.

A further embodiment of any of the foregoing methods can further includethat the metal layer has local thicknesses between about 0.102 mm (0.004inches) and about 5.1 mm (0.200 inches).

A further embodiment of any of the foregoing methods can further includethat the metal layer an average thickness between about 0.254 mm (0.010inches) and about 1.91 mm (0.075 inches).

Thus, plated polymer structures and components may provide impactresistance against both hard and soft body objects while yieldinglighter and/or less costly structures and components as compared totraditional manufacturing techniques.

INDUSTRIAL APPLICABILITY

Plated polymer materials such as plated polymeric substrates, platedpolymeric composite substrates and plated polymeric composite layupstructures may be used to form lightweight but strong parts of gasturbine engines, such as a layshaft cover, a case, a component of anacelle assembly, a fan inlet duct, a component of a thrust reverser,bulkheads, fixed panels or structures that may be used for soundattenuation, etc. The plated polymeric gas turbine engine components mayoffer cost and/or weight savings compared to baseline parts. The platedmetallic layers provide properties such as erosion resistance that canremove the need for erosion coatings on a composite case or cover.

What is claimed is:
 1. A fan blade for a gas turbine engine, the bladecomprising: at least one polymeric substrate forming a fan blade airfoiland having at least one exposed surface; and at least one metallicplating layer deposited on the at least one exposed surface of the atleast one polymeric substrate, wherein the at least one metallic platinglayer has at least one area strengthened by bonding the at least onearea to another metal-plated or metallic component using transientliquid phase bonding and the fan blade is located in a fan section ofthe gas turbine engine.
 2. The blade of claim 1, wherein the at leastone polymeric substrate is formed into at least one of a root and aplatform.
 3. The blade of claim 1, wherein the at least one metallicplating layer is selectively deposited on the at least one exposedsurface providing vibration control.
 4. The blade of claim 1, whereinthe at least one metallic plating layer is selectively deposited on theat least one exposed surface providing an electrical grounding path. 5.The blade of claim 1, wherein the at least one metallic plating layerhas an average thickness of 0.254 to 1.91 millimeters.
 6. The blade ofclaim 1, wherein the at least one polymeric substrate has localthicknesses between 1.27 and 50.8 millimeters.
 7. A gas turbine engine,the engine comprising: a plurality of fan blades comprising airfoils,each airfoil of the plurality of fan blades including a first at leastone polymeric substrate having a first at least one exposed surface; anda first at least one metallic plating layer deposited on the first atleast one exposed surface, wherein the first at least one metallicplating layer has at least one area strengthened by bonding the at leastone area to another metal-plated or metallic component using transientliquid phase bonding and the plurality of fan blades are located in afan section of the gas turbine engine.
 8. The engine of claim 7, furthercomprising a fan case surrounding the plurality of fan blades, the fancase comprises a second at least one polymeric substrate having a secondat least one exposed surface and a second at least one metallic platinglayer deposited on the second at least one exposed surface.
 9. Theengine of claim 8, further comprising at least one ice impact paneldisposed on the fan case, the at least one ice impact panel comprises athird at least one polymeric substrate having a third at least oneexposed surface and a third at least one metallic plating layerdeposited on the third at least one exposed surface.
 10. The engine ofclaim 7, further comprising a plurality of discrete fan platforms, asingle discrete fan platform of the plurality of discrete fan platformsis disposed between adjacent airfoils, each discrete fan platformcomprises a second at least one polymeric substrate having a second atleast one exposed surface and a second at least one metallic platinglayer deposited on the second at least one exposed surface.
 11. Theengine of claim 10, wherein the each discrete fan platform of theplurality of discrete fan platforms comprises at least one endwall, theat least one endwall comprises a third at least one polymeric substratehaving a third at least one exposed surface and a third at least onemetallic plating layer deposited on the third at least one exposedsurface, wherein the third at least one metallic plating layer ispolished.
 12. The engine of claim 7, wherein the first at least onemetallic plating layer has an average thickness of 0.254 to 1.91millimeters.
 13. The engine of claim 7, wherein the at least onepolymeric substrate has local thicknesses between 1.27 and 50.8millimeters.
 14. A method of fabricating a fan blade for a gas turbineengine, the method comprising: forming at least one polymeric substratein a desired shape of the fan blade for a fan section of the gas turbineengine; depositing at least one metallic plating layer on at least oneexposed surface of the at least one polymeric substrate, wherein the atleast one metallic plating layer has at least one weak area; and usingtransient liquid phase bonding to bond the at least one weak area toanother metal-plated or metallic component and strengthen the at leastone weak area.
 15. The method of claim 14, wherein the desired shape isat least one of a root, a platform, and an airfoil of a fan blade. 16.The method of claim 14, wherein the at least one metallic plating layeris selectively deposited on the at least one exposed surface.
 17. Themethod of claim 14, wherein the at least one metallic plating layer ispolished.
 18. The method of claim 14, wherein the at least one polymericsubstrate has local thicknesses between 1.27 and 50.8 millimeters. 19.The method of claim 14, wherein the at least one metallic plating layerhas an average thickness of 0.254 to 1.91 millimeters.